One very common way to establish that a male character is a Nice Guy (even if the niceness is hidden under a gruff exterior) is to give him an instinctive desire to be a big brother to smaller, younger, weaker or female characters. These other characters may be truly younger siblings, or they may be completely unrelated, or even older, but the feeling is the same; acting as their protector. Female examples exist, though in a smaller proportion.
The Big Brother Instinct serves to explain why fan attraction to Moe tropes and devices can be an emotional, rather than sexual, response. There seems to be something inherently comforting to an awkward male about being looked up to by a younger girl for support. Therefore Moe can be wish fulfillment about taking a "big brother role" instead of about being a Love Interest.
If both characters are male, the older (or in the case of twins, the physically stronger) brother will usually act as the younger/smaller brother's protector, to the point of treating him like a child, even when the younger brother is fully capable of protecting himself. This behavior can come across as loving and nurturing or as condescending and smothering. If the older brother goes to extreme, morally questionable lengths for the sake of the younger sibling, then they are a Knight Templar Big Brother.
Compare Big Sister Instinct, Mama Bear, Papa Wolf and Promotion to Parent. Contrast Big Brother Bully.
Has nothing to do with the TV show Big Brother. The 1984 meaning of "Big Brother" is covered under Big Brother Is Watching.
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Anime and Manga
Brock from Pokémon takes care of nine siblings when his parents hit the road.
Kenshiro from Hokuto No Ken. While usually brooding and serious, one of the few things that makes him genuinely crack a smile is being around Bat and Lin. Hurt or threaten Bat and Lin and, well, You Are Already Dead.
Rei's initial motivation for fighting was a pure case of this as well — his little sister Airi was kidnapped by Jagi on her wedding day and sold into slavery.
Guy Shishioh in GaoGaiGar. Just hurt or threaten Mamoru in front of him and start counting how long it takes for him to wipe the floor with you. Mamoru even calls him "Big Bro."
Code Geass gives us the trope picture and many examples.
Lelouch started a war for their little sister? Then there's his reaction to her possibly falling in love with Rai, the main character in the Dating SimLost Colors, though that one is Played for Laughs. He also intended to set Nunnally up with his best friend Suzaku, who cares about her almost as much as Lelouch does. Things get derailed when Suzaku is revealed as a Britannian mecha pilot, but by the end of the series he's the one taking care of Nunnally after Lelouch dies — which is exactly what he planned from the start.
Cornelia similarly has this going on for Euphemia. Prior to their exile, she also treated Lelouch and Nunnally this way, and she falls back into old rhythms when she reunites with Nunnally near the end .
The Chinese officer Li Xingke has one of these for his lady of liege, the considerably younger Empress Tianzi. It's implied that his love for her (and vice versa) is the reason that she can't be "conveniently" married off to a Britannian prince by the Eunuchs.
Kyon from Suzumiya Haruhi set himself up as a Stoic in the novels for ages. Being the Unreliable Narrator that he is, we can all see that he's Not So Stoic. Still, he was just annoyed when Haruhi grabs him by the collar and slams the back of his head onto her table and it was mainly because she disrupted the class.
During the filming of their amateur, plotless movie, Haruhi gets Mikuru to drink alcohol, trying to get a certain effect out of her. He almost attacks Haruhi. Let us repeat. He almost attacks a reality-warping goddess.
In the 7th book, Mikuru is kidnapped. Kyon flies into a rage (for the second time in the novels), and immediately calls up Haruhi for help, forgetting she still doesn't know she's a Reality Warper. He claims it was a failed practical joke to cover up.
In the 10th novel after Yuki is incapacitated by the Sky Canopy Domain Kyon completely loses it and runs out to track down Kuyo Suou and personally make her fix it. To reiterate, he actually went out of his way to get into a confrontation with an alien interface who he knows has god-like powers. Naturally, he's out-classed but it's the thought that counts.
Mai Tokiha from Mai Hime has a Big Sister Instinct towards her kid brother Takumi.
Shattered Angels: Kyoshiro and Kazuya. It's a bad one too; people die. Quite a few people, actually.
A much straighter example would be Tsubasa and Souma in Kannazuki no Miko: the entire conflict between them stems from Tsubasa's desire to protect Souma as effectively as possible, which unfortunately involves pulling him to The Dark Side and killing his love interest. Towards the end, however, Tsubasa recognizes that Souma has wishes, too, and helps him to reach his goals. Also, Tsubasa killed their father who beaten up Souma when were very young, which is why they were separated.
Mad Scientist Komui Lee is fiercely overprotective of his younger sister and only relative, Lenalee. The only way to wake the fiercely lazy Komui up is by saying "Your sister's getting married!" Since SHE is the one of the duo with the monster-killing super powers, he's got a lot to worry about. The reason he joined the Black Order was to be with Lenalee, who was kidnapped by them after she was found to be compatible with Innocence, and kept trying to escape to find her brother. Thus, the two keep each other in the Order. His obsession with his sister is mildly creepy.
Link even weaponizes this at one point, threatening Allen with telling Komui that he's alone in a sealed room with Lenalee if he doesn't unlock a door that's shutting the good inspector out.
In Cardcaptor Sakura, Yukito jokes that, despite Touya's teasing of Sakura, he has a protective instinct when it counts, something he acts out, secretly aware of her Magical Girl alter life.
played straight or inverted (depending on whether he is oldest or not) Syaoran acts as this towards his cousin Meiling in the anime adaption. His treatment of Sakura evolves somewhat into this at first (even if it ultimately becomes a somewhat different relation by the end of the series).
Zigzagged in Saint Seiya, when Ikki beats the stuffing out of his younger brother but then turns around again and again for the rest of the 100+ episodes, to the point where the Reluctant Warrior younger brother getting hurt in a fight became a sure-fire way to summon Ikki from his lone wolf brooding cave, screaming bloody murder and mind rape (in anything not drawn straight from the original manga).
Haré+ Guu: Haré has a big brother instinct towards his frequently irresponsible mother. Guu teases him about his "Mazacon" (mother complex) from time to time.
Averted and subverted (naturally) in Revolutionary Girl Utena with Nanami and her brother Touga. Whereas Nanami's big brother complex is extreme to the point that she is in love with him, Touga couldn't care less about her well being. Enter Mitsuru, a fourth grader, who she uses as a whipping boy after he saves her. She sees him as her servant, and he is fond of her-in fact, Utena and the others suspect that Mitsuru has a crush on Nanami, but he reveals that he wants to protect her like a brother would, unlike Touga. During his Black Rose duel episode, this is mentioned in the form of him being sexually and emotionally confused. It's shown that his interactions with the teenage Nanami piqued his curiosity about being grown-up, so he reads books about "adult"-related topics.
Subverted again (and to a twisted level) with Akio and Anthy. The former needs the latter to be the Rose Bride and forces her to suffer emotional and physical hardships such as being impaled with a million swords every time Akio tries to open the Rose Gate, the end goal of the duels, and forcing her into sex on a weekly basis. By the end of the series, though, she decides to leave him at last after God knows how long, yet despite his protests, he doesn't pursue her.
Played straight in Mawaru-Penguindrum with the Takakura siblings. The whole plot is based on Shouma and Kanba trying to save Himari's life. Even if she is not related to them by blood and just got taken in by the family.
Kanba deserves special mention since he not only has protective (and romantic) impulses towards Himari, but also sacrificed his position in the Natsume clan and later his life for his real sister, Masako (and Himari).
Ayaka claims to have an overdone big sister instinct which her friends and the viewer apparently grossly misunderstand.
Asuna has a more genuine version, that occasionally threatens to misunderstand itself.
Kaede also feels this way towards both Negi and Kotaro: A Love Chart produced in-universe shows that her romantic feelings for Negi are fairly low, but her maternal score is off the scale, surpassing the quite motherly Chizuru (10), matching Evangeline (12) *
May be due to being still in love with Negi's "late" father, wishing she was the one who bore the man's child(ren), et cetera.
, and topped only by Asuna (15). This doesn't always show mostly because of her laid-back personality.
Love Hina: Keitaro takes on a big brother role towards Shinobu early on, which does result in her developing an ongoing crush for him.
Seto Kaiba. He's a total jerk to the main characters, but threaten, kidnap or harm Mokuba in anyway, and he will make you regret it.
Jounouchi Katsuya is very protective of his little sister Shizuka. When she sends him a video message telling him about how she is slowly going blind, he sneaks into the Duelist Kingdom tournament that Yuugi was invited to so he could win the prize money and pay for an operation to save her eyesight. He also becomes extremely protective over her when Honda and Otogi begin flirting with her and competing openly for her attention.
Ishizu is completely willing to die if it means saving her little brother, Malik, from his psychotic Split Personality.
Strawberry Marshmallow: Nobue is a female version, serving the protective role towards her 12 year old sister and her friends. She also feels a near sensual pleasure watching them act cute, making her an easy victim of their manipulations.
Digimon: This is a continuous theme throughout nearly every season. Some have this problem with actual siblings, and others tend to apply it to their Digimon.
In the first season there was Yamato towards his brother and the youngest Digidestined Takeru. Hikari spends a good bit of Digimon Adventure 02 trying to live up to her big brother Taichi's reputation as a leader. And let's not even get started on Ken Ichijoji, who's desire to live up to his dead brother's memory in his parents eyes was the start of his whole descent into darkness.
Taichi is overly protective of Hikari before 02 though. The best example, episode 48, when Hikari falls ill and Taichi borders on hysterics the entire time. Then we find out why he's so over-protective (Taichi took Hikari outside to play while she had pneumonia, and she almost died.)
The twist of the knife is that Hikari never blamed Taichi for it. Quite the opposite: Hikari apologized to Taichi for not being able to kick the ball straight, which only made him feel worse and want to protect her "kind heart" even more!
Jyou/Joe shows a bit of this towards Iori/Cody in 02. Though he did have some inklings of this to Takeru/TK already in the first series. Somewhat justified by the fact that he's not just the oldest of the main characters— he's also got two older brothers of his own!
In Digimon Frontier, everyone was like this towards Tomoki/Tommy, but he seemed to especially look up to (and be stuck with) Takuya and Junpei/JP.
Kouji and Kouichi. It went both ways, but especially Kouji towards Kouichi.
Daisuke/Davis seemed to behave like this towards his Digimon partner, Veemon.
In Digimon Savers, Masaru/Marcus and his Agumon were like that (Masaru even admitted that he thought of Agumon like his brother). Masaru also was very protective of his little sister.
Ikuto/Keenan and his Digimon partner, Falcomon, were raised to believe they were brothers, and treat each other accordingly.
Then there's Touma/Thomas, who has a little sister whom he acts quite the same towards as Tai.
Another example from Digimon Adventure — Sora acts extremely protective of her partner Biyomon, eventually spurring her Digivolution into Garudamon.
In Digimon Tamers, Jenrya was rather overprotective of his youngest sister Shiuchon. This behavior turned out to be a bad influence on her when she got her own partner.
In The Prince of Tennis, if you mistreat Yuuta Fuji in almost any way, get ready to face his older brother Shuusuke's rage. Just watch and compare Fuji's matches with Jiroh Akutagawa and Ryoma Echizen ( both of them defeated Yuuta but did so fairly, so Fuji holds no grudges and considers Echizen a friend) with the one against Hajime Mizuki ( who tricked Yuuta into using a very dangerous tennis move without telling him the consequences, so Fuji let Mizuki lead the game for a while and then absolutely trashed and traumatized him in-game). No wonder Fujicest is among the most popular yaoi pairings in the fandom. Also, lampshaded in the anime when Fuji aids a girl with similar problems towards her older sister.
Kyo Kara Maoh: Shori has a certain obsession with protecting his younger brother at all costs.
Gwendal is very protective of Wolfram, and at times Conrad, though it is hard to see at first due to his stern nature. Conrad is very protective of Wolfram and Yuuri. Though Yuuri is the king, so he should be protective, he is Yuuri's godfather, and thus often acts like an older brother/father figure.
Conrad seems to have had a genuine 'Big Brother Complex' over Wolfram when he was small. The transformative episode when, at a guess, Conrad was about forty (looked twelve) and Wolfram was about fifteen (looked three) in which Gwendal sorted out his relationship with Dan Hiri, Conrad lost his father, and Wolfram found out his favorite awesome brother was half human appears to have started the trend that terminated in his behavior at the beginning of the show: calling Gwendal as 'Aniue' and Conrad as 'Weller,' his surname. And once Wolfram rejected him, Conrad eventually moved on to obsess over someone else. With a period of cynicism in the middle, out of which Gunter knocked him by kicking his ass.
Will go even more on a tangent to say that Gunter and Conrad's abortive fight in the Dai Shimaron arc was awesome.
In True Tears Jun displays this kind of attitude toward Noe, his younger sister. Hiromi even comments on it. In fact, he seems to be rooting for a romantic involvement with her, making it a case of Brother-Sister Incest even if it is one sided and never actually accomplished
Fullmetal Alchemist: The main plot revolves around Ed scouring the earth for a way to restore his younger brother Al's body to normal. On the other hand, considering Al is inhabiting an animated suit of armor much larger than Ed, there's a quite unusual dynamic going on there. Especially considering how Ed reacts to anyone calling him short.
Ed sacrificed his arm to keep his brothers soul in existence. And later, his use of alchemy altogether. If that's not Big Brother Instinct, what is?
The Elrics both have this dynamic towards each other. Edward was more than once willing to die for Al (until he realized that if he died no one else would be able to put Al back to normal) — and Al did NOT approve of Edward's plan to let himself killed by Scar so latter one would leave Al alone.
Scar's older brother. When Kimblee attacked, he jumped in front of Scar even though the effort was... well, fruitless. Afterwards, as Scar lay dying with one arm gone, his brother sacrifices his own arm and bleeds to death in his place.
At the end of the 2003 anime, Alphonse sacrifices his recently Philosopher's Stoned self to revive his brother. Edward answers this with sacrificing himself to bring Al back. In the movie, they spend much time, stress and tears to find each other again after this ordeal, and although they succeed, circumstances are such that Edward decides to leave his brother for good and seal the Gate from his side, in order to protect Al and Amestris from Dietlinde Eckhart - and Al replies with following him to the far side to be with him. That's FMA for you...
The first anime and one of the novels also feature the Tringham brothers Russell and Fletcher. Russell is very protective of his brother, though it takes him a while to realize that otherwise he's been neglecting him. He gets better.
In Bleach, one of Ichigo's biggest Berserk Buttons is an older brother harming his younger sister. He gave us the page quote.
Though he's still nothing compared to Orihime's brother, Sora. He's really possessive of his sister, even after death. He is shown to have become extremely jealous that Orihime likes Ichigo, and to put it in his words, "I wanted you to pray for me, because only during the time you were praying for me your heart was mine."
And in his back story, he ran away with a three year old Orihime from their abusive parents as soon as he turned eighteen, and proceeded to raise her on his own before being killed in an accident.
Ichigo has no problem suggesting murder if you mess with his little sisters.
In the Hell Verse movie, when Yuzu dies, Ichigo's Berserk Button is broken in the On position until Renji stops him.
Gundam X: Subverted with Shagia and Olba Frost. Not only the siblings in question are villains and brothers (instead of brother and sister), but the one who blindly adores and fiercely protects his sibling is Olba, the younger of the duo.
South Italy hates his younger brother North Italy's ally Germany because he thinks he's not good for his sibling (and since both Germany and Romano are male Tsunderes.)
According to Word Of God, Norway acts similarly towards Iceland. Confirmed in a strip, where Norway tries to make Iceland call him "Oniichan" (an honorific that usually little kids use towards their older brothers) and strangles Denmark with his own tie when he cracks jokes about it.
England also acted as an older brother figure to America, in his own way. The Revolutionary War thus broke his heart, and he still seems to have a soft spot for him (not that he'd ever show it).
Challengers: Souichi is fiercely protective of his younger brother Tomoe (as well as homophobic) and will not hesitate to pummel Kurokawa when he shows an overt romantic interest in Tomoe.
Naru Taru: Female-female example: Action Girl Shiina has a Mysterious Protector in the form of one of the "Otohime" or "Virgin Princesses". It turns out that said protector is actually her dead older sister, Mishou, who was transformed and reincarnated into an Otohime after her death.
Trigun: Knives is this way about Vash, but it's a really dark version, since Knives thinks that Vash's idealism and pacifism aren't doing him any good, and need to be beaten out of him.
Incidentally, they're twins, and no one was there to see them born. When Vash explains who Knives is in the anime, at least, he uses the absolutely-ambiguous word 'kyoudai,' 'sibling,' which carries neither gender nor age, because Japanese doesn't have a birth-order-ambiguous version of 'brother.' (The same word is applied to all their 'sister' bulb-plants in the manga. Confusingly, it's supposed to be an English-speaking planet.) Knives appointed himself big brother after becoming evil and deciding Vash was a wimp.
Anime Knives always had Big Brother tendencies, but in the manga back when they were still cute Knives was the sensitive one, and Vash actually looked after him slightly more than the reverse.
I.e., pointing out that even if Knives is right and "there's no real difference between people's hearts and ours," it's going to take a lot of work, and comforting him when Knives starts crying after William Conrad, the first human they ever met besides Rem, accepted them.
Anime Vash interpreted Rem's last words, "Knives o—" [mouth forming three inaudible syllables] as "Take care of Knives," though the meaning of this appears to have shifted in his head to mean 'beat the shit out of Knives' by the time they meet in July.
Basilisk has Saemon Kisaragi and his younger sister, Okoi. Even when Okoi is quite able to defend herself, all of the Koga Manjidani know that upsetting her is a bad idea not just because she'll punch them immediately, but because the ruthless Saemon will be NOT amused as well. When Okoi dies very messily, Saemon throws all his possible reservations about the Iga/Koga showdown away and fights furiously and without any mercy (except to Hotarubi, and that's ONLY after he's fatally injured her) to avenge his dead sister.
Peacemaker Kurogane: Tatsunosuke is overly protective of his younger brother Tetsunosuke. The other characters tease them both about this.
Fairy Tail: Mirajane and Elfman are a weird example of this: Elfman (technically the younger brother) is extremely protective of Mira, probably due to their dead sister Lisanna, for whose death he blames himself, flying into a rage when she's in danger and threatening anyone who flirts with her. However, Mira is also deeply protective of him, and rightly so, considering that she's about a million times more badass.
Haru acts this way towards Kisa, including running through the rain to find her after she runs away and giving her the strawberries from his cake.
In Kashimashi: Girl Meets Girl, Tomari'scrush on her formerly male best friend, Hazumu, comes out of her sisterly instinct to protect her. In the anime that protective side gets a bit less attention, though, and her feelings for Hazumu are presented more as a straightforward crush.
Vocaloid- although technically all the canon Vocaloids are supposed to be siblings- has Len Kagamine, who in vids is protective or over-protective of his sister, Rin, although Rin is supposed to be the older one.
In Getter Robo: Armageddon, Go immediately adopts this attitude towards Kei upon encountering her. It's eventually revealed that the reason for this is that he is her older brother — or rather a (male) memory-retaining clone of her older sister, Michiru, who died when Kei was a little girl... known as Genki Saotome. Sort of. It's complicated.
Subverted in Death Note where Villain Protagonist Light Yagami in an early Motive Rant claims that part of the reason he wants to make a better world is to protect innocents like his little sister, Sayu, and he has a Pet the Dog moment early on helping her with her homework, but later in the series considers killing her when she becomes a hostage so that the source of his power doesn't fall into the hands of criminals (Though ultimately he doesn't).
Early on, he suggests that he'd have to kill her if she found out about him being Kira.
It's possible that one of his first genuine reasons for killing off evil people was to make a better world for his family, but that changed as the Death Note began to affect him (and turned him into the crazy monster that he would become). This is backed up by his treatment of his family when he lost his memories.
Actually, according to the story we're told, his goal was to make Sasuke a hero of Konoha. The only way he'd be allowed to continue to live there after the entire Uchiha Clan planned a rebellion. Itachi was supposed to kill all of them, but he couldn't make himself kill Sasuke. That's one for the "Nice Job Breaking Your Little Brother, Hero" category.
Let's put it this way: Itachi was torn between the clan and the village, and ultimately chose the village. For the sake of his home, he willingly killed aunts, uncles, cousins, his lover, his father, and his mother...but he couldn't kill Sasuke. Because in the end, while Itachi may have loved Konoha more than his own clan's ambitions, he loved his little brother above everything else. This is shown in the ultimatum that Danzo gave him; either he died with his clan, or kill all of his clan, and they would spare the only child innocent of the Uchiha Clan's sins-Sasuke.
Kankuro is a more positive example. Although he and Gaara have a poor relationship at first, the brothers become much closer after Gaara's Heel Face Turn, and Kankuro willingly risks his life to go after Gaara when the latter is kidnapped by Sasori and Deidara - although it doesn't end well for either of them - and stands up for Gaara when an elder badmouths him. Considering how terrified he was of Gaara in Part 1 (and with good reason!) this is quite a change and shows just how much Gaara's change in circumstances has affected the family dynamic.
A is very protective of B, choosing to sequester him in the village to train rather than risk him in combat missions.
Darker than Black: There is a reason Hei goes completely nuts when his Dead missing sister is brought up. Namely, the reason he came to be a Bad Ass martial artist in the first place was to protect his Contractor sister. That's right, the normal sibling wanted to protect the one with superpowers. And did a pretty good job up until Heaven's Gate somehow fused them. In the second season, he starts treating Suou as a substitute little sister.
Of the few redeeming traits of Ryo Narushima in Shamo is his protectiveness towards his younger sister.
Fushigi Yuugi has Tamahome (towards his siblings, and initially, Miaka, after she told him she missed her actual brother Keisuke) and Tasuki (towards Chiriko).
Hayate sees himself as Nagi's protector/big brother and it's possible that he tries to exemplify it for all of the girls around him, possibly because of his own big brother's influence.
It even extends to Wataru and possibly Kazuki. There's only one other character he won't protect, even going so far as to try and kill. Continually.
The Katsura sisters have a warped version. Yukiji protected her sister when their parents left them with a large debt, taking care of it herself and shielding Hinagiku from the 'evil' side of society. Now she looks up to Hinagiku as the more capable one, having dealt with their abandonment and still having a loving outlook on life, while Hinagiku herself protects Yukiji and is hinted to help her with funding issues from time-to-time, while still punishing her for 'get-rich-quick' schemes she attempts.
Game X Rush has this for his younger brother Memori, particularly when Memori was a younger crybaby.
In AKIRA, Kaneda feels this way towards Tetsuo, because they were friends since childhood. Even though he teases him, he still feels the need to protect him and shows affection for him as a younger brother.
Seto from Heavens Will has one of the weirdest Big Brother Complexes ever. His younger twin sister died protecting him from a malicious spirit and her soul was sealed in a fan which Seto now uses to perform exorcisms himself. He then grew out his hair, began wearing woman's clothing, and is saving his money to get a sex change operation. After he gets it, he plans to kill himself so his sister's soul to inhabit his body and live again, and he does it all because he believes that he should have died instead of her. 'Seto' isn't even his real name, it's his sister's.
Baccano has two examples: Maiza, who serves as a sort of Big Brother Mentor to the young gangster Firo (who is supposedly somewhat similar to his biological younger brother, who was murdered in a conflict over the Elixir of Life), and Dallas, an unrepentant Jerk Ass whose one redeeming trait is his kindness towards his little sister. The three Gandor brothers are also very protective of one another.
Baskerville has this towards Mingchao in Et Cetera. Partially because he's dealing with his own little sister's death.
In One Piece, Portgas D. Ace is very protective of his adoptive little brother Luffy. This goes from taking on Blackbeard to sacrificing his life against Akainu.
Also Zoro to Chopper, who keep an eye out for the little guy and becomes upset when anyone hurts Chopper.
Kaiser Ryo for his younger brother Sho in Yu-Gi-Oh! GX, at least atfirst. Saiou for his sister Mizuchi in Season 4. A strange case is Fubuki for Asuka, in that he both attempts to get her to date other guys and manages to convey Brother-Sister Incest undertones simultaneously. Regardless, he does care for her as a sister, but usually it's her that ends up saving him.
In Magical Girl Lyrical Nanoha, Cinque of the Numbers is quite protective of her younger sisters, staying behind to fight Subaru (who is in the middle of a terrifying berserker rage brought on by the Numbers hurting her own sister Ginga) and getting badly injured in the process to allow Nove and Wendi to escape. Even though her crimes are more severe than the other Numbers and she does not expect to ever be completely free, she decides to atone for them and cooperate with the investigation so she can help her younger sisters.
In Yakitate!! Japan Kawachi does this to Azuma, due to Azuma having to worry about Kawachi. When Kawachi lost the battle with Kanmuri in the Pantasia Newcomer's Battle
Katekyo Hitman Reborn!. Any person willing to injure Kyoko or Tsuna, answers to Ryohei's fists and Tsuna's family.
Durarara!!'s Shizuo Heiwajima is rather protective of his little brother Kasuka (aka Teen Idol Yuuhei Hanejima). The mere act of namedropping Kasuka is enough to make him suspicious of your intentions, while insulting him or attempting to poke into his personal life results in an instant Unstoppable Rage. In the Light Novels, he eventually goes on to develop another Big Brother Instinct towards a young runawayYakuza Princess.
In Binbou Shimai Monogatari, Kyou has this toward her younger sister Asu, which is justified since they live by themselves and she has taken on a parental role. Since Kyou is still very much a child herself this doesn't always come easy for her, but luckily Asu compensates by often acting very mature for her age.
Fujimiya Ran in Weiss Kreuz goes so far as to take his little sister Aya's name after she's rendered comatose; he becomes an assassin primarily to pay her hospital bills, and not only is he fiercely devoted to her welfare, he displays knee-jerk protectiveness toward anyone who reminds him of her. This is most evident in his interaction with Identical Stranger Tomoe Sakura, but it also flavors his behavior toward several other young women and makes him a Big Brother Mentor toward Sena in Gluhen and Yuki in Side B.
Toki from Code Breaker is part of the Code Breaker group in order to keep his sister Nenene safe (though she's apparently older than him, and doesn't remember who he is).
Ozma Lee from Macross Frontier is extremely protective of his little sister Ranka, even though she's adopted. He even manages to break the pineapple cake curse because he promised not to die so long as Ranka still needed him. Also played straight with Brera Stern, Ranka's real brother.
Shannon Casull plays this trope straight in Scrapped Princess even if Pacifica isn't his biological sister. In fact most of his best moments this trope.
Demon prince Kougaji cares deeply about his half-sister Lirin and would do anything for her.
Gojyo's half-brother is this, despite being on opposite sides with Gojyo and feels tremendous guilt for not being able to protect him from the abuse of his mother. His extreme protectiveness over Kougaji is motivated by how he couldn't keep his biological half-brother safe and a way to gain redemption for not being able to. His complete psychological breakdown when he thinks he couldn't keep Kougaji safe reflects this.
Inverted in Rave Master where younger brother Haru is fiercely protective of his older sister Cattleya. He had once beaten up a guy who broke her heart and would have done it again when he ran into the guy later on in the series.
Soukou No Strain. After Ralph Werec has his Freak Out in the backstory (brought about by unknowingly brutally killing a bunch of aliens who look and act like little girls) he views the only survivor of the aliens as a substitute little sister, and is more than willing to do anything to avenge her race, and I mean anything, to the point of wanting to kill his actual younger sister when she stands in his way.
In the Wild Series, Kiri has a strong caring instinct for his little brother, Mao. Granted, it doesn't stop him from immediately trying to kill Mao when Mao loses control of his beast side, but he probably considered that a favour.
In Yu-Gi-Oh! 5Ds Crow shows this attitude towards; Leo, Luna, Yusei, Akiza, Jack and his younger siblings. To the point where he'd become the Idiot Hero
Guache of Tegami Bachi has this for his little sister, Sylvette. Until he looses all of his memories, anyway.
Maho from Wandering Son may be a bully to her little brother, but don't you dare mess with him.
Ouran High School Host Club plays with this with a few of its members, most notably in the episode where Nekozawa's little sister Kirimi wanders up to the high school, putting both Nekozawa and Tamaki in the big-brother spotlight in turn.
In addition, Hunny and Mori have this relationship with their brothers Yasuchika and Satoshi (manga-only), though Hunny's way of showing it is admittedly...weird, to the point that the anime completely overlooked it.
And Hikaru and Kaoru, being twins with a lot of identity issues to work out, go back and forth on treating each other this way. Usually Kaoru takes up this role while guiding Hikaru to maturity, but when he gets too self-sacrificing for his own good Hikaru will press his big-brother advantage to set him straight.
Lin from Spirited Away becomes quite protective over protagonist Chihiro over the course of the film.
Lin: Don't worry... stay right where you are, I'm coming to get you! You're gonna be fine, I won't let him hurt you.
Lin: No Face! If you put even one scratch on that girl, you're in big trouble!
In Saint Beast, Kira attacks anyone who so much as talks to his brother Maya initially. Considering the Fantastic Racism they are usually subject to, this is somewhat justified, but it also scares off potential friends.
Natsuki from tsuritama over his little sister Sakura, to the degree that she's one of the very few things that can crack through his grumpy demeanor and get him to smile. Haru saying to Sakura that Natsuki'll be teaching him and Yuki how to fish is the only reason Natsuki agrees to do it, just to keep her from feeling let down.
In Persona -trinity soul-, Ryou used to be like this 10 years ago. After their family reunited he turned out to be Aloof Big Brother. His younger brother Shin also have this toward their youngest brother Jun. Shin is really worried about Jun, he really worried when Jun came back home 30 minutes late than usual, including peeking him on his date. But it turns out that it was not really a date.
Mikoto: They are my sisters. It's because these little girls are my sisters. That's all there is to it.
Accelerator has this dynamic going on with Last Order, although some interpret it as more of a father-daughter relationship.
In Anatolia Story, Yuri initially mistakes a servant boy named Tito as her very young sister, who was lost when Yuri was kidnapped to the past. She quickly befriends Tito, and does not take it well when the queen tries to use him as a pawn to kill Yuri. When Tito is sentenced to execution for trying to kill Yuri (a member of the royal family by law, as she is disguised as Prince Kail's concubine) while Brainwashed and Crazy, Yuri runs in, argues down the executioner, and finally convinces Kail himself to call it off. When Tito is trapped in the queen's castle, after rescuing Yuri, she flies into a massive panic to have him rescued, openly accusing the queen of lying when the queen insists that she has no idea what happened. And when poor Tito shows up Flayed Alive, Yuri promptly declares vengeance on the hired grunt who did it, as well as on the queen for ordering it.
In Gakuen Babysitters, Ryuuichi is well-known amongst his peers for having this toward Kotarou.
Kurando from Popcorn Avatar is very protective of his twin sister Mafuyu, to the point where people accuse him of being a massive siscon. Indeed, he could initially care less about Lisa's motivations for saving the world, but is willing to play along because saving the world means saving the place where his sister lives in.
In Blue ExorcistRin and Yukio play with this. Rin is certainly protective of Yukio, but that was mostly in childhood as Yukio is now tough enough to handle himself most of the time. On the other hand Yukio is actually very protective of Rin and has sworn to protect him: but Rin is badass enough on his own and Yukio secretly hates and envies his older brother.
Ayumu of Kore Wa Zombie Desu Ka tries his best to get Eucliwood to call him "big brother," but the closest he comes is being called her "manservant."
Sousuke is this to a male example, Shino, in Hakkenden Touhou Hakken Ibun. He is the protective, motherly kind. Examples of his behavior include draping his coat over Shino when he was cold and then letting him fall asleep in his lap, carrying him on his hip like a toddler, and overall just fretting over him. He disciplines Shino and never forgets to tell him to mind his manners and take care of his strength.
The Mighty Thor: Thor treated Loki this way in early flashbacks to their childhood; however, it only aggravated Loki's already raging inferiority complex, putting him on the path to villainy.
However, after Loki accidentally (YMMV) brought about the near-total destruction of Asgard, was killed in a last-ditch heroic sacrifice to save what was left(that may have been part of The Plan) and reincarnated as a kid with only his childhood memories, he appreciates this protection a lot, since the only reason most people in Asgard haven't killed him yet is because they know Thor would go on a Roaring Rampage of Revenge on them and the city if Loki is harmed.
Kid Loki seems to be similarly protective of Thor. During the "Fear Itself" event, he engages in dark dealings and agrees to restore the Ragnarok Cycle all to save Thor from being killed by The Serpent.
Though they can find it hard to get along, Cyclops still tends to treat Havok this way, insisting on carrying his coma-ridden brother into the X-Mansion despite the presence of a wheelchair and being so protective and interfering that they're mistaken for a couple in an issue of X-Factor.
Batman: Between Nightwing and (adopted) little brother Tim Drake - one issue had Tim believed to have been killed by the Joker when a mass Arkham escape was in progress. Nightwing then beats the Joker to death with his bare hands, it didn't help that the Joker decided to bring up how he had also killed Jason Todd (another one of Nightwing's adopted little brothers). The Joker was just lucky Batman was around to revive him.
Catwoman tends to be a female version of this whenever she acquires a female tag-along who's too old for this to be considered Mama Bear.
Dick and Batman's biological son Damian, who eventually softens up to Dick, though he probably wouldn't say it out loud to Dick.
Dick's relationship with everyone he knows, him being on both ends. Be they a Titan, Leaguer or a Bat, Dick will make sure to get you messed up for harming them. Be they a Titan, Leaguer, or Bat, they will make sure to get you messed up for harming him. As Jason Todd found out, even if you're his brother, you do NOT hurt one of the other brothers.
Occurs with (intentionally invoked) Unfortunate Implications in American Born Chinese: When the Chinese boy Jin starts to date his classmate Amelia Harris, an Anglo friend strongly urges Jin to stop, saying he wants her to "make good choices."
Do not threaten Kanae in front of Kyon in Kyon: Big Damn Hero. Do not try and kill Kyon once he's done teaching you why you shouldn't attack Kanae. She may not be his little sister, but he treats her like one.
In Axis Powers Hetalia's Fanon, it's a known fact that America is protective of his twin brother Canada. Sometimes, he's portrayed as an over-protective brother whenever another nation is interested in Canada.
There was this one story (based on Vocaloid's "Servant of Evil" series), where Russia had killed Canada, mistaking him for America. Bad move, as America promptly declares war on Russia.
It also works the other way around. In a lot of fics, if America is hurt or captured, Canada is the one to rush to his rescue, in the most badass ways possible.
It goes the same way with Russia and his two sisters Ukraine and Belarus. There was this one story where Ukraine had mysteriously vanished, Russia believing that America was the one doing it ( He didn't) grabbed him by the throat and for all measures, was perfectly willing to rip America's head if it would bring his sister back.
In the fanfiction Awakening, America and Canada both act as big brother figures and protectors to the children being kept by Joseph Mengle. Given howhistory went, it]] really ends badly. Until the end, when it's revealed that they did inspire at least two of the surviving kids to keep going until their lives got better. Aw!
In the Batman fic The Choice of Family, it was inverted when Tim and Damian angrily called out Jason for putting Dick in danger and having him end up at the hospital. But it was played straight in the sequel Antidote for the Poison where Jason was furious when he found out Tim was injected with a dangerous amount of heroin by some drug dealers. When he cornered said drug dealer, who knows what he might have done if Damian wasn't there.
"You took my little brother, tied him up, pumped him full of heroin, and left him to die in this shit hole. Now I ask you: do you think I have the slightest bit of remorse about cutting you open and letting your guts decorate the floor?"
Jason also openly acknowledges Tim and Damian as his younger brothers and brings Damian safely home after he and Damian go out to get the drug dealers.
Raonar, the Guile Hero dwarven prince in Dragon Age The Crown Of Thorns develops some advanced protective tendencies towards the dwarven commoner, Faren, as evident when the former finds the latter trapped in his worst nightmare during the Broken Circle questline in the Fade. The resolution with the sloth demon can be seen as a partial subversion, however, because it's Faren himself who, ultimately, curbstomps the demon before the protagonist sends him over to Justice to be dealt with properly.
A female example in The Legend of Spyro: A New Dawn is Cynder towards Ember. Ember is slightly younger than her, but is very childish and naive. Despite the fact Ember has her characteristic crush on Spyro (though in this case, it's due to being to socially naive to realize Cynder and Spyro are mates), Cynder ends up having this mentality towards her, even describing her as being like "an annoying little sister" at one point. This makes hurting Ember in front of Cynder one of her Berserk Buttons, which Cyros finds out the hard way when she performs a Break the Cutie on Ember and gets her kidnapped. Cynder reactsviolently.
Fanon often have Gaara and Kankuro of Naruto threatening Shikamaru in Shika/Tema Fanfics or any other Fics that involve Temari getting hooked up with someone. They're technically little brothers as Temari is the Eldest Sibling.
It also doesn't help that Gaara is in fact the Kazekage, which means he has some authority over Temari. To which he abuses or at least attempts to abuse said authority.
In the Death Note fanfic Xanatos, Matt shows this toward Linda, most notably in chapter 3.
In Harry's New Home, the normally law-abiding Percy snapped when he found out someone tried to use the Cruciatus Curse on Ron.
The Powers Of Harmony: When Shining Armor sees a weakened Twilight dueling Trixie in Chapter 25, he remembers his training telling him to never charge into a situation without proper understanding of it first... then ignores it, because as he puts it:
"No one picks on my little sister."
Like in South Park canon, Kenny McCormick is incredibly protective of his little sister Karen in The Ballad Of Stoot And Argyle, sometimes to the point of ridiculousness. This instinct becomes even stronger when Kenny thinks anyone might be interested in Karen romantically.
Karen: My brother says the older boys are off-limits. They're not… he says none of them will be interested in relationships, per se.
Brother Bear: Kenai hates bears, and finds Koda REALLY annoying, but would still go through anything to protect him.
He likely gets it from his own brothers. His oldest brother dies early on in the movie, protecting Kenai from the Mama Bear he angered. His second-oldest brother spends the movie in a misguided attempt to kill Kenai in bear form, mistakenly thinking that bear-Kenai killed human-Kenai.
Fly in Help Im A Fish, who's pretty caring when it comes to Stella, his little sister. Case in point: When it seems like searching for her in starfish-form in the ocean via boat is hopless, he doesn't hesistate to drink a potentially dangerous potion and dive in, in order to continue searching.
In The Prince Of Egypt, Ramesses's first reaction to his little brother killing a man in front of multiple witnesses is to declare him innocent. When Moses returns after years of being gone he is ready to give his brother a high position and wipe away the crime. That didn't work out.
There's also Moses's biological brother Aaron, who tries to protect Miriam when they first encounter Moses, who at this point is still considered Egyptian royalty and therefore a threat to them.
In Joseph King Of Dreams(a kind of Spiritual Sequel to Prince Of Egypt), Joseph's many older brothers plan on having this when their baby brother is born. Unfortunately, a whole lot of Parental Favoritism sours that, leading them to sell Joseph into slavery in Egypt and tell their father he was killed by a wolf. At the end of the movie, it's revealed that the brothers feel immense guilt over what they did and are very protective of Benjamin, to the point where, when Joseph tries to arrest Benjamin for a crime that wasn't committed, all of the brothers offer themselves up in his place. This moves Joseph enough to forgive them all.
Disney's Robin Hood has the titular character acting this towards Skippy and the other children. After the Sherif takes Skippy's birthday present (a gold coin his family saved for him), Robin Hood comes in to cheer Skippy up and gives him a bow and arrow and his hat. Later on, when one of Skippy's sisters struggles to catch up with the escaping villagers from Prince John's castle, Robin Hood doubles back to get her.
In Toy Story 3, Andy is this to his sister, Molly, despite their light bickerings. When she had trouble lifting a box, he immediately went to help her. And at the end, with Bonnie, who is a Shrinking Violet. He kneels down at eye-level to her and introduces all his toys to her and played with all his toys one last time with Bonnie before he left.
Jack Frost in Rise Of The Guardians acts much like an older brother to all the children around him. It makes sense as what led to him becoming a guardian was him sacrificing himself to save his little sister from drowning.
The title character of Wreck It Ralph is this towards Vanellope. At first he wants nothing to do with her, especially after she steals a medal that he believes will earn him the respect of those he works with. As the two spend time with each other, and seeing they are Not So Different, Ralph becomes protective of her.
Film - Live-Action
The Blind Side: With only a split second to act, Michael instinctively saved adoptive little brother SJ from being seriously injured or killed during their car accident.
He also will not tolerate anyone saying something derogatory about his adoptive little sister, Collins.
Also, from the same movie, Kayla appears to be willing to do anything to keep her sister safe.
X-Men: First Class: Darwin develops this for the younger mutant recruits, especially when Shaw attacked the CIA base. Unfortunately, this only gets him killed by Shaw when he tries to protect Angel from him.
Also Charles had this for Raven, being very concerned for hiding her appearance in public and telling her to her face that he didn't want anything to happen to her. However, his relationship to her Deconstructs this phenomenon as it caused him to become overprotective to the point where he denied her the chance to embrace her true appearance and be proud of what she was, as well as caused him ignore her very obvious crush on him. This in turn made Raven turn to Erik Lehnsherr as a mentor/love interest and eventually join him in his cause against humanity.
Arguably, Erik developed this for Charles. He went out of his way to protect Charles during the Cuban Missile Crisis, even stopping his attack on the American and Russian naval forces when Charles was shot.
Star Wars: He's only the big brother by about six or seven minutes, tops, but Luke Skywalker definitely qualifies. He's all redeeming and peaceful and unflappable in the face of evil despite a million reasons not to be, but all bets are off when the Big Bad makes an impotent, hinted threat towards his sister. Suffice to say, he doesn't react well.
Han Solo to Luke Skywalker. Despite always calling him "kid" and having doubts about Luke's plans, Han becomes fond of Luke early on and often goes out of his way to protect or rescue him. In "Empire Strikes Back" he risks his own life by going out into dangerously low temperatures to find Luke after he doesn't return to the rebel base.
The Godfather's Sonny Corleone, in spades. He launches into one of the most epicNo Holds Barred Beatdowns in film history against his brother-in-law after he finds his sister with a black eye. The enemy family Barzini later uses this instinct against Sonny by paying Carlo to deliver a savage beating to his wife in order to easily set up an ambush for Sonny.
Seen in West Side Story when Bernardo interferes in his sister Maria's budding romance with Tony. Double Subverted in that Tony is the only decent member of the Jets, genuinely in love with Maria and with good intentions... but then he ends up killing Bernardo in a fit of rage over the death of his friend.
In the extended edition, there's also a scene where Éomer finds an unconscious Éowyn after the Battle of Pelennor Fields. He holds her and cries, before getting her medical attention.
Peter Garret in Vertical Limit climbs up K2 to rescue his sister Annie
The titular character of Ginger Snaps is an interesting example - her protectiveness towards her younger sister is essentially, a snarky sense of humour aside, her only redeeming quality, and that's pretty messed up. They have a suicide pact ("Out by sixteen or dead on the scene,") and her gradual case of lycanthropy worsens, she starts killing people if she thinks they even looked at Brigitte the wrong way. She's enjoying killing more and more, so this trope becomes more of an excuse in the end. However, Sam could be seen to have a genuinely altruistic Big Brother Instinct towards Brigitte, as he gives her an awful lot of help, carrying a fair amount of risk, with no benefit whatsoever to himself. Although some people interpret it as him having a romantic interest in her.
Becca from The Descent is very caring and protective towards her sweet little sister Sam, and to a lesser extent, the rest of the less-experienced caving group. Also, it's fairly subtle, but Beth displays Big Sister Instincts towards anyone in the group who needs it - she's constantly looking after the emotionally fragile (due to the death of her husband and child) Sarah, she gives her jacket to Holly after she breaks her leg and helps her stand and walk (along with Sam, The Medic) and she goes back to help Juno in the crawler fight, even though she doesn't like Juno much.
Aussie horror flick Black Water is actually rather sweet in spots due to it's use of this trope. Initially, we have both Grace and her boyfriend Adam towards Grace's shyer, more panicked sister Lee. However, Lee turns out to have a Little Sister Instinct herself. You see it emerging slowly throughout the film, but once Grace is injured, Lee is willing to face down crocodiles if it means she can get her sister out of there and to a hospital. Turns out she's just much braver for her sister's sake than she is for her own.
In K.A. Applegate's Animorphs, Tom does everything he can, which isn't much, to keep his brother from being infested and goes nuts at the thought of the Yeerks getting to Jake. Jake displays a similar protectiveness towards Tom besides being younger. Also, Elfangor towards Ax.
At one point in the series, when Jake and Controller Tom are talking (which they do often, being brothers, obviously), "Tom" lies to Jake to cover his status as a Controller, and, if only for a second, Jake notices Tom's face twitch strangely. Jake suspects that Tom is trying so hard to fight against his Yeerk that he momentarily wrestled control of his body away from the Yeerk, which is established as impossible.
Harry becomes this to Molly when her magical talents manifest. It becomes quickly obvious that both are suppressing sexual feelings for each other, and Molly breaks first. Harry makes sure to keep their relationship as platonic as possible.
He does it to his half-brother Thomas despite the fact that Thomas is the older brother.
Thomas also has a brother instinct. He has followed Harry around town without Harry's knowledge, and in several books the only time Thomas hasn't come to Harry's aid was when the White Council was directly involved. He is also very protective of his little sister, Inari.
The movie version of Prince Caspian portrays Susan falling in love with Caspian. Peter definitely seems to oppose Caspian in every matter, getting to the point where they almost battle each other. It's almost as if Peter is destined, from the beginning, to hate the guy and bash him, while his little sister is instantly swept off her feet by him.
Peter has this pretty strongly toward Lucy as well. He vehemently rebukes Edmund for humiliating her in the beginning of the series, up to the point that he looks like he's about to deck his younger brother in the movie.
Ron Weasley reveals this in Harry Potter And The Chamber Of Secrets while nearly cursing Malfoy (with a broken wand that has already backfired once on him) for being mean to Ginny. The two best ways to get Ron angry are to insult either Ginny or Hermione.
Ron gets a bit of this from Percy after the Second Task in Goblet of Fire. Percy, who's supposed to be acting as an impartial judge give Harry full marks for rescuing Ron and hovers over Ron until Madam Pomfrey drags Ron off for treatment.
Eclipse Hunter: Devon falls under this trope very easily, and fills many different archetypes. He's willing to shoot his own father if it means protecting Daren.
In The Thief Lord, Prosper's protectiveness of Bo is the main motivation behind his character. He runs away from his aunt with Bo to prevent their separation, joins a gang of urchins and steals to make sure his brother is well fed and sheltered, and goes into a major Heroic BSOD when Bo is finally taken away.
The Darkest Powers series gives us Derek. He has a Big Brother Instinct that's Up to Eleven when it comes to his foster brother, Simon. Derek is also a werewolf. So on top of the fact that he is, personality-wise, very protective of Simon (and anyone else he cares about), he also has the wolf's "protect my pack" instinct to deal with. Assaulting one of his "pack" is his Berserk Button. Unfortunately for Derek, since he can't usually control his reaction when his brother is in danger no matter how much he's tried to coach himself, his supercharged Big Brother Instinct has led to at least one My God, What Have I Done? moment.
Len Maynard of Chalet School Practically ever since she is a baby, she is pigeonholed as the 'responsible one' and as the oldest Maynard child, she is often put in charge of the other Maynard children. She has a major one where Margot is concerned, protecting her from Jack's wrath and lying to cover up for her in Triplets of the Chalet School after the bookend incident. Miss Annersley even calls her on it.
Kaladin from The Stormlight Archive develops one of these for every relatively (around 14) young male he comes across in the course of the story. This stems from his feelings of guilt over failing to protect his actual younger brother in the course of a minor border dispute between rival lords of his nation. Every one of these individuals ends up dead.
The Cal Leandros series gives us Niko, who loses his characteristic cool when someone so much as implies that his brother is a monster, and goes berserk with rage when he thinks Cal is dead. Cal is no better, going to extreme lengths to protect his brother.
Although Damon Salvatore of The Vampire Diaries likes to make his brother's life hell, he does go out of his way to save or protect Stefan.
Katniss Everdeen of The Hunger Games will go to any lengths to protect her younger sister Primrose, including volunteering for the titular Deadly Game in her sister's place, a seemingly suicidal gesture.
Also Rue to her siblings, and Thresh to Rue. See their character page for how.
To a degree, Finnick Odair to Katniss, especially in Mockingjay. Katniss is enduring a Trauma Conga Line, and she is trying to take care of her little sister, and she is a symbol for a rebellion. Her "friend" Gale is wishy-washy and is usually either off doing suspicious work with Beetee or making passive-aggressive comments. Peeta is captured for the first half of the book, and psycho in the second. Her mother, while better than she was in the first book, is not necessarily helpful. Finnick, on the other hand, who is himself prone to trauma and currently enduring a seemingly endless case of PTSD, does all he can to make Katniss feel safe and comfortable, despite his own issues. Until he dies. Boggs is this too. Until he dies as well.
Prince Jonathan and his group of friends in Song of the Lioness developed this for the new page Alan. Even before Ralon started bullying Alanna, they regularly helped and kept an eye out for her. And when Ralon first beat up Alanna, Raoul pulled him aside and roughed him up as a warning. When Ralon later broke Alanna's arm in retaliation, they all thrashed him thoroughly. Despite continuing to harrass Alanna, Ralon didn't lay a hand on her again.
And both Alec and Seregil are always and at any time rather protective towards Beka (in Seregil's case it is also a rather paternal feeling; he states himself she's as close for a daughter to him as it will ever get.) - including being suspicious about her lover, checking him up, threatening him not to harm her... Beka is not impressed.
Tamir Triad: You better not insult Tobin when his squire/best friend Ki is around. (and in fact thanks to plot this brother-friendship later gets rather difficult)
An even creepier example might be the ghost Brother. Tobin's older twin who died after birth and turned into an angry spirit. After Tobin learned how to keep him in check Brother actually got extremely protective - despite the claims of some characters this troper never could shake the feeling that Brother DOES feel affection and brotherly love towards his sibling. Albeit in a twisted way.
In The Outsiders, everyone was this towards Johnny since his abusive parents could care less about him. Also, Ponyboy's two older brothers Sodapop and Darry, especially after their parents' death.
Brandon Stark was this for his sister Lyanna in the backstory to A Song of Ice and Fire. When Crown Prince Rhaegar Targaryen abducted and raped her, Brandon rode off to King's Landing with a few companions to kill Rhaegar and rescue his sister. It didn't go well....
Jaime Lannister is this for both of his siblings. Technically, his sister is a minute or two older than he is, but that's hardly the most complicated thing about their relationship. For the first few books, at least, he'll do anything to protect them — and if it involves killing someone, so much the better.
All the Stark siblings are (usually) close and would fight for the others, but Jon Snow particularly is this for Arya. And later, after a rocky start, fills a similar role towards some of his Night's Watch brothers.
In a gender-reversal, the tough and practical Meera Reed acts as a protector to her much frailer younger brother Jojen.
It's not all happy families in this series, though: this trope is averted heavily in several cases, most dramatically by Gregor Clegane.
Genna Frey (nee Lannister) mentions that when her weak father agreed to betroth her as a seven year old to Emmon Frey (a second son, and thus a somewhat insulting match for a girl of her rank,) Tywin (himself only 10 years old at the time,) publicly called out their father and Lord Frey for it being a poor match. While she says she did not approve of everything he did as an adult (or even enjoy his company that much,) she couldn't help but love him as a protective big brother.
In Ender's Game, the reason that Ender was willing to go to Battle School and join the International Fleet was to protect his sister Valentine, although he was actually her little brother.
In the In Death series, Roarke tends to harbor protective instincts toward Eve's female colleagues, though they're not particularly weak. This is probably due to his dead little sister.
In The Voyage Of The Jerle Shannara, Quentin Leah already has a pretty serious big brother complex towards his cousin Bek. Following his failure to save a girl he liked, this is magnified a thousand fold, and helps to fuel his change into a badass.
Bertie of Jeeves and Wooster tends to develop this easily. In one story he suddenly decided that he wanted a daughter for precisely this reason: "Something to look after, if you know what I mean."
As mentioned above, Dr. Watson to Sherlock Holmes. A word of advice: don't be in the same room with Watson if you're threatening the Great Detective. You might be threatened with a chair.
The feeling is mutual. Althought he usually comes off as calm and composed, Holmes does not take kindly to people trying to hurt Watson. In the story "The Adventure of the Three Garridebs", a criminal they are trying to apprehend shoots Watson in the leg. After having a minor panic attack and ascertaining that it is only a flesh wound, Holmes lets the criminal know in no uncertain terms that if he had killed Watson, he would nothavegottenout of the room alive.
Psmith seems to feel this way about Mike. They're the same age (they met at Boarding School), but Psmith acts much older. Try to fire Mike from his job, and you'll get blackmailed.
Averted, oddly enough, with the eldest sister. Zarracka can't stand any of them. In the sequel she develops Aunt Instinct for her nephew, Benji.
In the sequel, Legacy of the Dragokin, Ravage is joined Jiahdain's group because his little sister was already part of it and he wanted to keep her safe.
Eldest Whistler in A Brother's Price is this way to her whole family, including sisters-in-law - as she declares, "We Whistlers have an unbreakable rule - you mess with one of us, you mess with us all!" - but particularly her vulnerable brother Jerin. When she believes he was raped by the crown princess, she plans to kill the woman but is enough of a Reasonable Authority Figure to listen to him. Most of Jerin's sisters are like this to some degree. Even Corelle is motivated by the desire to protect him.
Marcus demonstrates this towards Julia in The Mark Of The Lion trilogy (at least until her betrayal of Hadassah at the end of book one, after which he declares This Is Unforgivable), and is the only one who indulges her more headstrong tendencies manifesting from her being Spoiled Sweet.
Live Action TV
In Smallville, while they are about the same age, Clark tends to have this towards Chloe. Very much justified given the first three guys she tries to date (not counting Clark himself) all tried to kill her (Sean in Cool, Justin in Crush, Ian in Dichotic). Also because he is Superman and she is an ordinary girl who isn't even particularly good in combat.
Even when they are adults and after Chloe had her first marriage, this behavior persisted. In Escape, when Clark finds out Oliver and Chloe has just been Strangled by the Red String, he says that she has been through a lot, and that Oliver should never take her for granted.
With being six years older, and coupled with his Lonely Rich Kid past, Lex Luthor very frequently felt this way towards Clark Kent in the early seasons of the series. Even going as far as to sometimes dip into Berserk Button territory whenever the young farm boy was threatened or harmed.
On White Collar, Peter and Mozzie both have a very strong big brother instinct when it comes to Neal. The problem is, they almost always have different ideas about what actually constitutes looking out for him.
Which adds an extra layer of heartwarming to their park bench meetings in Withdrawal. They're both so worried about Neal that they actually make an effort to get along with each other and try to figure out the best way to help him deal with Kate's death.
Simon And Simon: Brothers Rick and A.J. both exhibit this trope. Although Rick is older, he and A.J. are both protective of each other, as shown in almost any episode.
iCarly Spencer in regards to Carly and Gibby to his little brother Guppy.
The Colbert Report: Stephen Colbert has admitted he sees Jon Stewart as something of an older brother figure in Real Life. It's one of the few Real Life traits that bleed through into the characters' lives, most recently in the Mêlée à Trois crossover with Conan O'Brien, which Stewart only got involved in because he was protecting Colbert.
Buffy the Vampire Slayer: Spike takes pains to keep Dawn from harm in a few episodes, when Buffy or the Scoobies are unavailable to do so.
Face and Murdock show this for each other quite a bit. Murdock is older than Face, but they both have their share of 'big brother' moments when it comes to looking out for each other.
Also, B.A., towards both of them. He's allowed to verbally abuse them and threaten them with physical violence on a regular basis, but if anyone else tries it...
A little odd in his case, seeing as, when you do some figuring, B.A. may actually be younger than Murdock, and possibly younger than/the same age as Face. He's still protective of them. But he'll never admit that he likes either of them, especially not Murdock.
Angel: Played for laughs in an episode, when Angel and Doyle deliberately act in an over-protective fashion towards a prospective boyfriend of Cordelia's in order to mess with her.
Angel actually is a big brother, and his evil alter ego Angelus killed his little sister.
Captain Mal Reynolds extends something like this to his entire crew, but particularly Kaylee, whom he even refers to as mei-mei or "little sister" a couple of times.
Inara is also very willing to play the Big Sister role. "Mei-mei" is most commonly used by her towards other (usually younger) female characters.
Everybody to Kaylee
Everwood has a lot of that: Bright starts off being a bully in the pilot, but later on in the same episode it's revealed he cares a lot about his younger sister and her comatose boyfriend. That's also expanded throughout the first season, to the point that his friendship with Ephram stems from his desire to keep her sister happy (in real life, Bright's and Amy's actors actually dated). It could also be mentioned that Ephram was protective of Delia, and Dr Abbott also became sort of a father figure to his sister after their father died (even though they were both already adults).
Gossip Girl: Chuck and Serena with Eric (or is it Erick?), Dan with Jenny (especially on the pilot). Lily's siter also counts.
Jane Lynch's character in Glee: pure evil, except for her ill sister.
Finn has developed this for Kurt, especially since their parents got married. The exchange between him and Burt when Kurt decides to come back to McKinley says it all:
Burt: Keep an eye on your brother.
Finn: Way ahead of you.
Justin, from Wizards of Waverly Place, always fixes Alex's mistakes and saves her from impending doom. She even admits that she always expects him to do so.
And a serious one because the fans have started asking the producers if Justin and Alex are going to end up together. It's DisneyChannel, after all.
Subverted in the Cold Case episode "Shuffle, Ball Change". The victim's brother was simultaneously protective and fond of his younger brother, yet he derided his ambitions to be a dancer and ultimately murdered him in a fit of jealous rage over his impending success (along with grief over his own failure as a wrestler).
Dean and Sam Winchester, of Supernatural. This is a show that's actually about being brothers. (The bromance being fashionable this decade.)
Dean Winchester is absolutely insane on this point. 'Take care of Sammy' has been his entire life motto. He dies for him, he sells his soul to Hell for him, he keeps going back for him no matter how screwed up things get between them and what Sam gets dragged into, he takes him back no matter what...and honestly the way the show is written, the latter two there seem to cost him more than the first. Especially seasons four and six, when Sam was slipping darkside and walking around without his soul, respectively.
Sam turns it back on Dean pretty hard, himself. Even in Season One he completely flew off the handle when Dean looked to die, and season three was all about saving Dean to him, and he lost it once Dean went to Hell.
And he overpowered Satan for Dean in the Season 5 finale. Sure it saved the world, but it wasn't the world he thought about. But he's actually four years younger, and Dean practically raised him.
The angel Castiel gets adopted as an unofficial third Winchester brother some time in Season 5.note This is codified in dialogue late in Season 6, when he's going darkside on them with the best intentions, like Sam did two seasons previous. Because he is young to the world and they are young to being and lack power, the 'big brother' role swaps back and forth a lot, and sometimes Dean and Cas are both big-brothering one another in the same scene. Though Dean never turns the Sam-level obsessiveness on Cas.
The evil thing doing an overwrite of Dean's mind and body in 7.06 complained that he "doesn't have relationships, no, he has applications for sainthood," which is just that raging protectiveness and self-sacrifice is the only setting he has for people he cares about. Which isn't to say he can't be a raging dick to these same people, because he can, but Big Brother's Privilege.
Actually that was referring to Dean tending to put the people he cares about on a pedestal and thus taking it pretty hard when they (inevitably) fail to live up to those expectations (most notably in Season 2 with John,Sam in Season 4 and Castiel in Season 6). As for being a raging dick: this is "Supernatural" and his behaviour is nothing compared what the rest of the characters - especially Sam towards Dean- pull (another thing he tends to overlook when in his "hero-worshipping mod" but that hit him pretty hard when snapping out of it -see John and Sam))
NUMB3RS: Don Eppes was always Charlie's protector and on the few occasions when criminals come after Charlie, Don becomes a Papa Wolf and decides that It's Personal . Don also shows concern that Charlie will be affected by the grim aspects of law enforcement and feels a little awkward accepting help that might conflict with Charlie's career as a professor.
Burn Notice: Michael Weston has this towards his little brother.
Bill Scully Jr. of The X-Files has a Big Brother Instinct for his youngest sister Dana, though he can be a jerk about it and doesn't always bother to get all the facts before lashing out at people he sees have "wronged" her...like Mulder. Poor Mulder.
Derek's just the most obvious. All of the characters have this towards Reid. Emily in particular joins Morgan in this, with her Older Sister-like relationship with Reid. For evidence, just look at her taking a beating in "Minimal Loss" to save Reid from getting shot, and this line from "Amplification":
Heroes: Nathan Petrelli to his little (26-year-old) brother, Peter. Sometimes... When it comes down to it, it's clear that he loves his brother. (After Peter saved him from dying, Nathan tells him flat-out he wouldn't have done the same .)
In Can You Hear My Heart, Joon Ha goes so far as to abandon his biological family to take care of a boy with a hearing disability.
We could be sure that Hassan from Over There was like this when Colonel Roye threatened him about his sister so he could tell him where the stingers are.
One from Power Rangers. Vida, the Pink Mystic Force Ranger, is already a pretty aggressive character. But threaten (or otherwise belittle) her sister Madison, and it doesn't matter whether you're an enemy or a colleague. Vida will tear you in half.
Barbara Havers of Inspector Lynley is a cranky, foul-mouthed junk food addict who can't seem to work well with anyone in the police force except her partner Thomas Lynley. On the other hand, she is incredibly good with children and will go to any lengths to protect them.
Bones: Booth and Brennan toward their psychologist, Sweets. His old mentor flat-out states in one episode that Sweets - raised in an abusive home, adopted by a loving older couple who then died when Sweets was in his late teens or early 20s - is subconsciously seeking to build a surrogate family with the pair.
There's also Booth and his younger brother Jared. Booth was willing to give up a massive RICO case which would have given him a promotion, a raise and a trip to Hawaii just to get Jared off on a drunk driving charge. He was also very dubious of Jared's love interest and actually did a background check on her.
ER: Many of the older staff toward Carter, but particularly Greene and Benton - the latter to the point of being a Papa Wolf.
The Vampire Diaries: When the tomb vampires kidnap and torture Stefan, his brother Damon massacres every vampire in the house.
The awesome moment when Elena utters these five words. "Stay the hell away from my brother."
Prison Break: Linc toward Michael, and Michael - though the younger brother - to Linc.
In Wonderfalls, much though Jaye finds her family irritating, she has a very strong Little Sister Instinct. In one episode, after a guy punches her brother (played by the rather tall Lee Pace), Jaye (played by the decidedly smaller Caroline Dhavernas) manages to lay out the guy with a single punch.
Jaye: You don't screw with my family.
Warehouse 13: Both Pete and Myka, towards Claudia. Just try watching "Breakdown," and not awwwing a little. For her part, in Claudia's introductory episode, she breaks right into the freaking Warehouse and kidnaps one of the main characters in order to force him to help her rescue her brother Joshua, who was zapped into an interdimensional space (and not, as initially thought, killed) twelve years prior.
In Merlin, Arthur and the rest of the knights seem to be developing this for Merlin during Season 4. All of them were horrified when Merlin nearly died saving Arthur from the Dorocha and then warmly welcomed him back when he recovered. This protectiveness is a little misplaced since he could easily take on all of them with his powers!
Merlin is also quite protective of Gwen, but then, so is eveyrone. It's been said before on this site: Seriously, don't mess with Gwen. It's a bad idea.
In Blue Bloods, Danny is this with both Erin and Jamie, but especially with Jamie, since his gut instinct in crisis situations seems to be making sure his "kid" is safe.
In Wishbone Sam see a team mate being picked on so she takes him under her wing and teaches him to play better.
In The Big Valley, Nick, Heath, and especially Jarrod are very protective towards Audra. There are good examples of this in first season episodes "The Midas Man" and "Last Train to the Fair".
In Family Matters Eddie occasionally had this relationship with Laura. When one of her boyfriends started a rumor that they slept together, Eddie angrily grabbed him and pinned him to the wall.
Good Times. For all his goofy, idiotic behavior and his constant teasing of Thelma and Michael, JJ proved over and over again that the best way to set off his Berserk Button was to harm either one of them.
In JAG Bud Roberts is this with his little brother Mikey. Also Harm is this with his Russian half-brother Sergei.
Subverted horrifically in one episode from the 2000 revival of The Twilight Zone. A lonely little girl bonds with her babysitters, who she sees as friends or sister-figures. The latest one realizes that her doll collection appears to be coming alive to attack the girl, and spends the episode fighting them to save her. It then turns out that the dolls were all the previous babysitters, who the girl transformed because she was upset that they "abandoned" her when her parents came home. The current babysitter promptly freaks out and tries to explain the concept of "hired caretaker" to the girl, and is turned into a doll herself for her troubles.
Sheldon acts this way to his twin sister Missy in The Big Bang Theory, however, it's subverted in that he doesn't do this so much for her sake, but because he concluded that in her loins lies the potential building blocks to create another remarkable genius like him. When Missy finds out his reasoning, she Groin Attacks him.
Matthew seems to develop this towards Tom in Season 3 of Downton Abbey.
Hank a.k.a Dr. Henry Lawson is always watching out for his little brother, Evan, in Royal Pains. After their mum passed away when they were very young, their father took off, leaving them to take care of each other. So Hank raised his little bro. We see an example of a protective Hank in season 4 episode 2 Imperfect Storm, whereby he goes into full-panic mode searching for Evan after a firework explosion.
In Psych, Shawn is seen several times threatening anyone who messes with his best friend (whom he sees as a brother), Gus - as he said in the finale of the Yin/Yang trilogy when Gus was being threatened, "You kill him, I kill you."
The Middle consists of three siblings - Axl the oldest, Sue in the middle and Brick the youngest. While Axl shows more affection towards his little brother, Brick, he's more emotionally closed off when it comes to his little sister, Sue. He taunts her, treats her with disdain, teases her to no end and belittles her very existence (he never tells anyone in his school that he has a sister), but when it comes down to it, Axl shows a softer, comforting side of him when it really counts. Examples would be in episodes like The Block Party (where he gives Sue his old Jersey because he felt bad for her not making ball girl), and The Paper Route (where he gives her a little pep talk after her boyfriend dumbs her for another girl, and invites her to come watch his game to cheer her up, awww!).
Surprisingly, this showed up in Scrubs, with J.D.'s normally antagonistic older brother standing up for J.D. against Dr. Cox:
Dan: "I just wanted to say a few things to you, Perry. I've never been much of a good example to my brother... Johnny will never look up to me, but when I see you two together he hangs on every word you say as if it's his entire world. If you ever let him down, you'll answer to me."
Tony Stonem in Skins starts off the series as a manipulative, cruel borderline Villain Protagonist. The one exception is his sister Effy. Her near-death experience at the end of series 1 causes his Heel Realization.
Apollo from Classical Mythology tricked his twin sister Artemis into killing Orion because he feared this was one guy she could give up her vow of chastity for.
To the great suprise of those who watched the movie Troy, Agamemnon in the origial Classical Mythology has this in spades. Paris fucked with Menelaus, Agamemnon will make Troy burn
More "little sister instinct" . St Angela Merici was grieved when her older sister died without rites. Then she received a vision telling her that her sister was in heaven. In gratitude she devoted the rest of her life to religion and service to the poor. Ah....
The Hardy brothers, Matt and Jeff. Matt as the older brother, both in story lines and Real Life, often plays this role. (When he's not this, he instead is the Jerkass.)
The Big Daddies and Little Sisters in BioShock are based directly on this trope. The Big Daddies are massive cyborgs that have been programmed to always watch over the Little Sisters and protect them at all costs, while the Little Sisters are conditioned to always stay close to a Big Daddy and rely on them for protection. Neither Big Daddies nor Little Sisters are aggressive and attack on their own, but unfortunately you need the ADAM the Little Sisters extract from corpses with huge syringes, which they don't give up willingly. And when somebody touches a Little Sister her Big Daddy will fight to the death.
Bio Shock 2 goes even further and puts you in the role of a Big Daddy whose Little Sister was taken away and who had been dead for 10 years. When he is revived, the Little Sister Eleanor calls for his help to rescue her from her mother's imprisonment. For most of the game you put half of Rapture upside down and tear through hordes of splicers to get back to her and save her.
As a Big Daddy you also have the ability to adopt other Little Sisters and have them harvest ADAM for you. This leaves them vulnerable to attacks from splicers for about a minute during which you crush the skull of anyone who is trying to attack her.
The main character (whether male or female), Akihiko and Junpei serve as adopted big bros (and sis) to Ken in Persona 3. Akihiko's issues related to his dead sister Miki mean that he also has some protective big brother impulses towards Fuuka and the female protagonist. Shinjiro is similarly protective towards Fuuka and constantly laments what happened in Ken's past.
In Persona 4, the main character acts this way towards Nanako Dojima, which leads to manymoments that make you go aaaww. In short, Persona loves this trope. Later in the story, Nanako gets kidnapped and thrown into the TV world, which not only stimulates a response from the main character, but from Yosuke, Chie, Yukiko, Naoto, Kanji, Rise, and Teddie.
Unfortunately if you take this into Knight Templar Big Brother territory and actually throw Namatame, Nanako's kidnapper, into the TV after her apparent death, it will lead to the worst ending, as Nanako stays dead, and everyone in Inaba gets turned into Shadows.
Persona 4 Arena reinforces this, with the mocking introduction the main character gets in the P-1 Grand Prix video: "Nobody touches his precious Nanako! The Sister-Complex Kingpin of Steel, Yu Narukami!"
Prototype: Mess with Dana Mercer, and your best bet is most likely being eaten alive by big brother Alex. Ironically, the character you play, Virus!Mercer, is a lot more caring about Dana than the real Alex Mercer, who was responsible for the virus to start with.
Resident Evil 4 : Leon sure does go to a lot of trouble for Ashley and seems genuinely compassionate towards her, even if it IS part of his job. Leon is only The Stoic when he's the one in danger, but he'll risk himself without hesitation to protect anyone who needs his help.
Chris Redfield is another example. Not only does he go to Antarctica to rescue his sister in Resident Evil: Code Veronica, but in Resident Evil he watches out for the youngest STARS member Rebecca and saves her from a Hunter.
Mega Man: Blues (Proto Man) can be very protective of Rock (Mega Man). He's gone out of his way many times to save his life instead, meaning he keeps an eye on him. He gives a lot of advice to him.
Rock himself is the same way. When Wily reprogrammed his brothers, he became Mega Man, took them down, sent them back to the lab to be reprogramed back to normal, and Then defeated Wily with a BIG LOUD CRUNCH!
And now with Mega Man 10 on it's way, it seems that Mega Man and Proto Man have teamed up to get the vaccine to cure Roll of Roboenza. Whoever created the virus needs to run away now.
Final Fantasy Tactics Advance: At least after Marche said he will take care of his brother Doned at the real world after they beat his group up at some cave.
Axel of Kingdom Hearts, towards Roxas, after he started essentially raising the amnesiac Nobody. Sort of a knight templar big brother, given how much of a Poisonous Friend he is. Often misinterpreted as Ho Yay since the whole "raising Roxas" wasn't shown until a sequel released several years after the game where the Big Brother Instinct was initially shown.
In the prequel game Birth by Sleep, Terra has this towards Ventus. Threaten a hair on that kid's head and it doesn't matter if you're Master Eraqus, he'll still beat you into the ground.
Also in Twilight Princess, he receives the same sort of treatment from Rusl, one of the villagers, who Word Of God specifically states considers Link to be his younger brother.
Sonic the Hedgehog treats Tails like a little brother. He will also protect him just like a big brother would, as Dr. Robotnik/Eggman learned the hard way in the 8-bit version of Sonic the Hedgehog 2.
Sonic sometimes take this role for Cream The Rabbit in several official media's and fanfiction's.
Less prominently, Big the Cat of all people seems to act this way to his Team Rose comrades in Sonic Heroes. He is shown comforting and defending Cream on several occasions in the story, Team Chaotix intimidating her marks one of the very few occasions he is genuinely pissed.
Luke, in the Franchise Professor Layton games, has a bit of a big brother complex toward Flora, despite being very obviously younger. It Makes Sense in Context — Luke's known the Professor for a long time and has assisted in a number of investigations, while Flora is a Fish out of Water in every situation due to her sheltered background, so both Luke and the Professor are protective of her.
Bartz in Final Fantasy V shows this towards Krile, when she joins the party after her grandfather's death. He doesn't treat her as weaker or in need of protection, but he does keep an eye on her to make sure she's okay emotionally.
Merrill, the ridiculously cute and adorably awkwardbloodmage of Dragon Age II seems to have the power to instill this in those around her. Half the party actively looks out for her, especially the amoral pirate captain and the dwarven spymaster, and Anders starts to look out for her, in his own extremist blood magic-hating way. The only one who truly dislikes her is Fenris, and he tries to get her to change her ways, albeit in the only way he knows how. Even Hawke can easily turn into this if s/he doesn't romance her.
Bethany Hawke as well. The first thing Hawke does when they meet Wesley is give the Templar a Death Glare, before he makes clear his intentions. This is the reason her relationship meter is heavily tilted toward "friend." That, and her baaad case of Big Brother Worship (not that the two are unconnected).
Carver shows glimpses of Little Brother Instinct, through it seems to be buried under a thick layer of Sibling Rivalry. He won't let Fenris threaten Hawke in his presence, and will be highly antagonistic towards Sebastian if he marries his sister.
In Baldur's Gate II, the Player Character gets to be this for Imoen who has been an actual half-sister of yours all along, as you discover. Granted, you can choose dialogue options that indicate you don't really care, but you still have to rescue her from Spellhold. If you play the game as a good character, though, you are this trope in spades.
Corpse Party has Satoshi Mochida, who has this for his younger sister Yuka. Yuuya Kizami, who Yuka meets after she and Satoshi are separated, is also looking for his younger sister. Except he doesn't have a younger sister and is, in fact, a subversion.
Luigi might have a bit of a "Little Brother Instict" when it comes to Mario. By that, he plowed through a planet-scale army by himself, with his bare hands, and didn't get hit once because Bowser kidnapped Mario.
For added humor, Ducio turns up years later in Brotherhood, still talking trash about Claudia, and Ezio gets to beat him up again.
He also has a cameo in Revelations. This time, the mere sight of Ezio sends him fleeing in terror.
King from Cave Story has is this towards Toroko. He gets angry when she refuses to give him the key to Arthur's house, but will also fly into rage when she gets kidnapped (and that's without touching red flowers, either).
Arguably Fang's overwhelming desire to save Vanille from turning into a Cie'th can be interpreted this way; bonus points for Vanille being visibly much younger and weaker in addition to being the cheeriest, cutest, and most tragic character of the cast.
Hugh, your rival in Pokémon Black 2 and White 2 is this towards his little sister, whose Purrloin was stolen by Team Plasma 5 years prior to the games, he mows them down at every chance he gets in his search for her stolen Pokémon.
In Fate/stay night, Heaven's Feel route, Shirou states that he wants to save Ilya just because "older brother protects his younger sister". In the route's end, Ilya herself does a Heroic Sacrifice to save Shirou, who actually is her younger brother.
Yuuya towards Sakuya in Hatoful Boyfriend. Sakuya claims that Yuuya has never once acted like a brother to him, but this couldn't be further from the truth as not only does Yuuya sacrifice his life to save Sakuya's in the Bad Boys Love route, but he reveals that he kept Sakuya's egg from being thrown away on his cruel stepfather's orders and killed his stepfather's own offspring so that Sakuya could take its place and live a life of luxury.
Lana Skye from Phoenix Wright: Ace Attorney comes across as an Aloof Big Sister to Ema, but as it turns out, she's been acting as a reluctant accomplice to Gant for years, all to protect Ema from the Awful Truth: that she accidentally killed Neil Marshall during the SL-9 Incident. However, Gant actually staged the scene to frame Ema and killed Neil himself, all so he could manipulate Lana's protective instincts and blackmail her into forging evidence for him whenever he saw fit.
In the School Days sequel of sorts Summer Days, Kotonoha's reaction to seeing her younger sister Kokoro in very... compromising situation with her prospect boyfriend Makoto is grabbing a golf club and hitting the culprit upside the head. Too bad Kokoro intercedes in Makoto's favor.
In Little Busters, Riki begins to feel this way towards Komari in her route when she confides that she feels sad that she keeps seeing a non-existent older brother in her dreams. Later, it's revealed that he did exist and felt this way towards her, too, in spades. On the flip side, Komari also tries to be a big sister towards Rin and Kud, though it doesn't always work out - in the test of courage, if you take both Kud and Komari, the two keep switching roles with one always scared and the other trying to act cool and comfort them.
Rin, Riki, and Kyousuke all play with the trope a bit. Kyousuke definitely dotes on Rin, but he also worries that she is too dependent on him. Rin herself is open about her lack of respect for him, almost always calling him by his first name and refusing outright to call him 'oniisan' or 'oniichan', but it's also clear that she deeply relies on and admires him. On the other hand, Riki has an admiration for him so strong it borders on the romantic...to the extent that in one scene Kyousuke admits that he thinks both Rin and Riki are cute and Riki worries that Kyousuke 'only' sees him as a little brother. However, like for Rin, Kyousuke is implied to also be worried that Riki relies on him too much, and in Rin's route he seems to be trying to challenge Riki into standing up to him and facing him as an equal. However, ironically, when he tries to break their dependence on him he does it in a way that seems to cement his position as the authority, assuming he knows what's best for them and manipulating them against their wishes.
Tomoya also seems to have this going for him, despite not having any siblings. Whenever Mei calls him Onii-chan, he becomes overly excited and is willing to do whatever she wishes from him.
Higurashi No Naku Koro Ni: Satoshi was like this toward Satoko before his disappearance to the point of murdering their abusive aunt brutally, even though he was usually calm and gentle, since he was under the influence of Hinamizawa Syndrome. A year later, Keiichi and Shion take up the position with Keiichi taking it in the completely wrong direction while Shion plays it straight, but only after screwing up. Big Time. Satoko actually starts calling them "Nii-Nii" and "Nee-Nee".
In one of the PS2 arcs, implied to be the way that Minagoroshi-hen could have gone, Shion goes exactly the same way as Keiichi.
In Umineko No Naku Koro Ni, Battler behaves this way both towards his actual younger sister, Ange, and to his little cousin Maria. He bonds with Maria early on in most of the arcs despite not having seen her in six years, and is very protective of Ange. After Ange reveals her identity to him and performs a Heroic Sacrifice, Battler snaps out of his funk and goes up several levels in badass and sets his mind back on track to defeating Beatrice and making it back home to her.
Occasionally Elliot has this towards Tedd, like here and here.
Grace's brothers also have some of this in them, though they don't show it nearly as much as Elliot does towards Ellen. Even though Damien scared them shitless, Hedge tried to subvert the orders concerning her as much as he could without being killed.
Ellen has shown she's just as willing to stand up for Elliot when he's threatened/hurt as viceversa. In her other life, this trope is more or less how she befriended Tedd.
Dominic Deegan tends to act this way toward his cheerful, overly optimistic little brother Gregory. Was kind of justified when the comic started because Gregory was infected with a necromantic taint that was slowly killing him, but it was removed early on and now he's perfectly healthy while Dominic is missing a leg.
Played with between Dominic, Gregory, and their older brother Jacob. Jacob spends significant amount of time and parts of major plot-lines trying to maim his little brothers for his own advantage, though he claims there's no emotion involved and it's just part a convenient part of his plans rather than malicious. And yet, he immediately does far, far worse to those who hurt them first.
Arthur from Wiglaf and Mordred has got a bad case of this for his little brother Mordred - so much so it tends to get in the way of his evil villainy. His staff often enjoy pointing out the brother complex he claims doesn't exist.
Most of the cast, but particularly Jason, behaves this way toward their younger friend Anna in Something Positive.
It would be unwise of you to mess with Bear's younger sister Patches.
Roy actually did have a little brother, (key word here being did), and Elan has a living twin brother but has been shown explicitly thinking of Roy as his brother instead.
Roy has a literal little sister, for whom he feels the same protective need (despite crazy moralitydifferences.) Proof? He went to rescue her from villains, knowing fully well that it was a trap all along].
In Lackadaisy, Viktor is violently protective of Ivy. To the extent that every boyfriend she wrangles is pounded to the point of a full body cast. This is particularly noticeable when you contrast it with how he reacts to others, which usually tops off at Vague Irritation at best.
Aiden in Winters in Lavelle has this towards his little sister, Kari. It's even been said by Keshii that the main reason why he dislikes Ashton is because he can tell that Ashton has a thing for his sister.
We're introduced to Elon of Ears for Elves when he's searching for his younger sister Myari after she's run off into the dangerous forest. He gives her a severe talking-to, but has her best interests at heart.
In Frankie And Stein, Frankie and Adam seem to have this relationship. They haven't really known each other that long, but Adam is very concerned for her, and her current crisis.
Red vs. Blue has Agent North, with such a trustworthy, older-brother instinct that he gets assigned Theta, the AI fragment composed of Alpha's innocence. He's the only one in the program qualified to take care of a being of pure innocence.
But seriously, watch seasons 9 and 10. The dude lives and breathes trust.
Blue team. Sure, Caboose is an idiot. But he's their idiot.
Wash eventually develops it for the Reds and Blues. In the flashback he tried to mimic North's, but CT wasn't buying it.
In Worm, this is a major part of Grue's makeup — in fact, his trigger event came when he was defending his little sister from his mother's abusive boyfriend.
In the comic Rebound, Mai takes down a room of Ozai loyalists to save her little brother from being indoctrinated into their father's radical group.
Mako from The Legend of Korra spent his childhood watching over his brother Bolin and he still is in his adulthood. When Bolin was kidnapped by the Equalists, he threw one of his captors across the screen Hulk-style, or in this universe, Korra-style.
Mako also slightly deconstructs this trope: He's sheltered his brother from the harsh realities and darker nature of their environment to such a degree its partially led to Bolin's current naiveté and dependency.
Bolin himself counts, too. When Korra receives gifts from Tarrlok in front of him, Bolin offers to "have a word with the guy," as he thinks she's being harassed by a Stalker with a Crush.
Noatak, better known as Amon shows a pretty dark take on this. He'll bloodbend his brother Tarrlok, but when their father goes a little too far he starts bloodbending him.
Danny Phantom: Danny does this with his Opposite-Sex Clone, Danielle. In the first episode they meet, he goes from suspicious to protective, keeping her safe from Vlad with his Ghostly Wail, the second time he was willing to be Valerie's captive if it meant saving her from being dissolved. Interestingly, he develops this instinct even with his older sister, becoming overprotective when she's in trouble or in the rare moments when she does something irrational.
The Simpsons: Bart Simpson usually couldn't give a damn what happens to Lisa on a mundane basis, and the two have an intense sibling rivalry, but his instinct does kick in every time something serious happens.
In "Black-Eyed, Please," Homer asks Ms. Krabappel to get rid of Lisa's bully subsitute teacher. You know what she does? She gets Bart to play a transfer student in the woman's class, and he then proceeds to cause absolute havoc during a two-minute bathroom break and makes the woman quit her job. While it isn't shown, the fact that Bart agreed to do this at all shows that he does care about Lisa.
Loopy's older brother Larry on KaBlam!'s Life with Loopy shorts is like that towards her.
Perry the platypus from Phineas And Ferb seems to be like this to the title characters, judging by how much more viciously he attacks his nemesis Doofenshmirtz when his current scheme would put Phineas and Ferb into danger.
In the movie Across the Second Dimension, Candace-2 from the alternate dimension is fiercely protective of her brothers Phineas and Ferb. To the point she is willing to abandon the alternate Phineas and Ferb to protect her own. Though she eventually came back for them.
Though not nearly to the same extreme, this also applies to regular-dimension Candace herself. Despite having a morbid fear of heights, she once rode a flying bicycle into space when her brothers got captured by an alien poacher.
Franklin Turtle, without a doubt, seen in the third season in "Big Brother Franklin" when Franklin took to looking after a little kid named Squirrel. He also became a "best friend big brother" to Bear's little sister, Beatrice. Eventually, Paulette Bourgeois finally made him a big brother for real in the book "Franklin's Baby Sister" and the film Franklin and the Green Knight soon followed.
Wild Kratts has the Kratt Brothers, who both play it straight and invert it. Most obvious in episode 32, when Chris goes missing after getting stuck to a bee, Martin is upset that he wasn't able to keep Chris from going missing and keep him safe, and he keeps setting out to find him.
In Generator Rex, Rex's older brother Cesar instantly goes into protective mode after their reunion and tries to 'rescue' Rex, even though Rex isn't in any danger. He later knocks out a bunch of Providence agents and jumps down from a ship to help Rex fight an Evo.
Winnie the Pooh isn't particularly smart to say the least, though he will constantly aid and comfort Piglet as much as his hapless self allows. Similarly Tigger is something of a Keet, though cares a lot about Roo. With a fair helping of Big Brother Worship in there from the latter, both even refer to each other as brothers. Both of these are seen in the original novels, though it is the Disney incarnations where this trope is most evident.
Tigger: Only the best...for my bestest little brother...
Kenny McCormick from South Park cares a great deal about his younger sister, Karen. So much so that he dresses up as his superhero persona, Mysterion, and acts as her Guardian Angel.Awww.
Alternatively and less immediate, Kyle and Ike's relationship has varied throughout the course of the show; originally, Ike was more of an Annoying Younger Sibling who idolized Kyle, following him to school and copying his mannerisms, while Kyle held a more superficial malice towards his brother (when he learned Ike was adopted, he completely shunned him for a while). Nowadays, Kyle goes to great lengths to keep his little brother safe, from stopping him from running off to Somalia, to dragging his friends to Canada on Christmas Eve to get Ike back from his biological parents. Ike has now become one of Kyle's greatest drives (seconded only to Kyle's antagonism towards Cartman.)
Not even that. Kyle was perfectly willing to let Cartman kill himself in Somalia, even the thought of other classmates following him did not budge him from his celebrations. Realising Ike had joined Cartman however completely reversed his feelings.
On Gravity Falls,Dipper seems to have this for Mabel, even though they're twins. For example, in one episode they work together to get back at Pacifica for hurting Mabel's feelings, only for Mabel to learn that she has nothing to prove to her. Dipper, however, says that he's learned nothing and gets revenge on Pacifica anyway.
And to an only slightly lesser extent, she protects him right back.
Thomas the Tank Engine is this to some of the other engines, especially Percy. This is especially prominant in later seasons, where he is more matured and experienced so often charged with keeping an eye on newcomers. Also inverted since he is sometimes this to older engines such as Toby as well.
Motorcity: Dutch is this towards his younger brother Dar, refusing to let him join the Burners after Dar realizes becoming a Kane Co soldier was a mistake.
Martin Mystery is a huge man-child that doesn't take anything seriously in life, except when any danger that comes to his slightly older stepsister, Diana. Examples of this are shown in every episode where she calls out for help and he comes straight to her rescue.
Jake Long, a.k.a the American Dragon has a very perky, know-it-all sister that grates on his nerves more often than not, but his brotherly instincts kick in if there are any signs of danger towards her.
Nightwing is this to the current Robin, Tim Drake in YoungJustice after the Time skip.
Given how the quarrel between him and Batman (leading to him quitting Robin to become Nightwing) never happened in this universe, he must have been close to Jason Todd as well; and after Jason's death, understandably he is more protective of Tim than ever.
Nightwing has this for all the younger team members. When the Reach kidnaps Lagoon Boy, Beast Boy, Impulse, and Blue Beetle, he orders the rescue squads to proceed despite the probability of discovery, only saying "Get our boys."
Other examples include Cheshire, who was ready and willing to murder to Aqualad when she believed he'd murdered her little sister; Miss Martian, who is scary protective of Superboy and Lagoon Boy (her boyfriends) and Beast Boy (her surrogate little brother); and Aqualad, who hates being the leader of the team but continues to, believing that Robin is too young.
Big Binky from one episode of Rugrats will go out of his way to protect his little sister Emma from harm(even if he won't take his binky out of his mouth).
Bobby Kennedy had a raging overprotective little brother instinct towards his big brother. Apparently, his fury could scare the shit out of anybody if they tangled with John. Especially if it was LBJ (Lyndon B. Johnson).
LBJ was no slouch either. He was a master at cajoling Congress into doing whatever he wanted because, damn it, he was LBJ. The fact that Bobby could match him and actually make him back down is pretty amazing.
James Mc Neil, age 17 saw his autistic ten year old brother climbing to the top of an 120 foot electrical tower. Though fearful of heights he climbed after him and held him in place until a rescue crew arrived. The story is described in the November 1997 Reader's Digest.
Members of a fraternity are supposed to develop this, as the house is set up for a big brother to look after a little brother (pledge).
A 12 year old Florida boys saved his four siblings from a fire.
On an unreleased Chappelle's Show "Charlie Murphy True Hollywood Story" the older brother of comedian Eddie Murphy tells how he had to be let go as head of security for Eddie's entourage because he got carried away with beating up anybody within earshot who would talk smack about his little brother. Going so far as to physically threaten a man paralyzed below the neck who wouldn't stop loudly cussing out Eddie in a restaurant!