Similar aspects- siblings, I would suppose, but opposites, one dark, the other light.
—Nafia, Secrets of the Dragon Sanctuary, Fablehaven
In real life, siblings hardly ever act the same. Fiction sometimes takes this to an extreme.
Enter Sibling Yin-Yang, the occurrence of siblings that are nearly polar opposites. If he's cool and reckless, she's responsible and thoughtful. If she's a spiky-haired hooligan, he's the nerdy wimpy one. If he's an immature brat, she's... well, you get the picture.
The even more extreme form leads to Different as Night and Day, or even Evil Twin. When this leads to complete antagonism, it becomes Cain and Abel. See also The Glorious War of Sisterly Rivalry . If an Aesop is involved, chances are it's a case of Foolish Sibling, Responsible Sibling.
The anime and light novels also have Fletcher and Russel Tringham, who present many parallels with the Elric brothers.
So much so that not only do they impersonate the Elrics at least twice, there's a certain amount of Sibling Yin Yang between respective imposters-the Tringhams fulfill a certain amount of the expectation of what you're going to get with the Elrics, which is quite different from what you actually get. Aside from the fact that each Tringham has an ego that matches his respective Elric.
Not to mention Alex and Olivier Armstrong (manga and second anime only). Alex Armstrong, a.k.a. Colonel Clean, is the almost grotesquely overmuscled poster boy for Pec Flex and prone to fits of staggeringoveracting at every possible opportunity, often with Manly Tears, and he's actually a total softy. His older sister Olivier is a Badass Normal of epic proportions, a slim, Magnificent BitchSocial DarwinistLady of War who can call Ed short without him even trying to argue and has no compunction about killing representatives from Central because they irritated her and pushing their bodies into wet concrete.
To be fair to the Major General, she says he irritated her, and by that means he confessed proudly to being involved in a soul-stealing murder conspiracy that amounts to betraying the whole country, and tried to take her men away.
To further the suspicions of an Expy] / Kyo AniShout Out, Tsukasa has a very similar hairstyle to Ryou. With the same hair color to boot.
Mermaid Melody Pichi Pichi Pitch uses it repeatedly. Caren is a brooding, grudge-holding Broken Bird, while her twin sister Noel is a forgiving, self-sacrificing Yamato Nadeshiko. When Caren got nicer and, as a result, dropped Out of Focus, she became a loud party girl to keep the opposite dynamic going. There's also Kaito and Gackto, of the Cain and Abel variety, as well as one being a friendly joker and the other a White-Haired Pretty Boy. Lucia and Nikora, though only posing as sisters, fit it too with The Ditz versus the Team Mom. In fact, it's even lampshaded in the Black Beauty Sisters, who are also definitely not sisters.
In Lucky Star, Konata lampshaded two pairs: Kagami / Tsukasa and Yui / Yutaka. Konata hypothesized this trope is caused by one sibling absorbing attributes from the other sibling.
Taken out of context by Minami, who says that Miyuki Takara must have absorbed something else from her, by virtue of being next door neighbors
Light and his sister in Death Note. Their only common points are that they are both good-looking and respected. She is a nice, ordinary person, he is a freakishly intelligent Well-Intentioned Extremist with sociopathic tendencies and a god complex.
Also Near and Mello, when you consider that they were raised side by side.
Twin examples: Risa and Riku in DNAngel; Vash and Knives in Trigun; Abel and Cain in TrinityBlood; Metatron and Sandalphon in Angel Sanctuary; Chrno and Aion/Ion in Chrono Crusade; Suboshi and Amiboshi in Fushigi Yuugi. Also note that as is often the case for the twin archetype, which some scholars view as a sub-category of the hermaphrodite archetype (seriously), one twin is gendered more 'feminine' (Risa, Vash, Abel, Chrno, arguably Metatron) and the other more 'masculine' (Riku, Knives, Cain, Aion, Sandalphon). (This has nothing to do with sexual orientation!)
This trope is even lampshaded by the twins in DNAngel:
Riku: We have absolutely nothing in common!
Risa: Nothing at all!
Another twin example: Yoh and Hao from Shaman King. Hao is an evil twin.
Soma and Kanna from Devil & Devil, Soma is a weak ocult otaku and kanna is a violent rebel, it doesn't help that they each get possessed by the devil Sword and the angel Ios respectably.
Yoh and Minatsuki in Deadman Wonderland are an interesting case: both are liars, cowards, and opportunists, but Yoh may be fundamentally a caring guy while his sister is a Yandere.
Jun Ushiro and his sister Kana in Bokurano. She is sweet, shy and forgiving, he is violent and brooding.
In Hajime No Ippo, there's Kumi Mashiba, Ippo's main love-interest and a Yamato Nadeshiko to boot. And then there's her big brother, Ryo 'The Executioner' Mashiba, an angry and brooding boxer who eagerly uses intimidation-tactics and fouls to beat down his opponents, and just generally comes across as a borderline psychopath. About the only person who's NOT scared of him is Kumi, who have been known to slap him to the floor when he got out of hand. There's also the fact that Mashiba practically raised Kumi ever since they were orphaned in an accident, so only she and one of his bosses know how hard Mashiba has worked to take care of her. The scene where this softer side of his' was shown was quite the Tear Jerker in the anime.
Yuma and Yuna Kashiwagi from Pani Poni Dash!. Yuma is an extreme extrovert (and borderline Yandere), Yuna is an extreme introvert. Yuma goes so far as to actively sabotage Yuna's attempts at being more accepted just to keep eyes on her.
The Chizeta princesses from Magic Knight Rayearth: Tarta the younger is loud, rude, and Hot Blooded while Tatra the elder is quiet, polite, and a total pushover (apparently), which is probably why the younger sister seems to be the leader.
Also, America and Canada: The first is a loud, outgoing mix of Eagleland archtypes and Boisterous Bruiser; the second is much more quiet, sensible, and overlooked.
Kouichi Kimura and Kouji Minamoto of Digimon Frontier. Aside from being twins, the holders of the spirits of Light and Darkness, and having the entire Separated at Birth thing going for them, there's even an episode named "The Brothers Yin and Yang."
The Nitori siblings of Wandering Son couldn't be more different. Big Sister Maho is outgoing and pushy. Little Brother Shuichi is timid and even feminine. This actually gets lampshaded by the pair's father, who relates to Shu a story of their grandmother betting Maho would be a boy and Shu a girl before they were born. Given the family's recent discovery of Shu'sissues, Nitori Sr. wonders if Grandma was really so wrong about them.
Ace and Luffy on One Piece. Ace is more level-headed and polite than his brash and bordering on brain-dead little brother. Even Luffy's crew have expressed disbelief at how different Ace is from their captain.
It has been revealed, however, that Luffy and Ace aren't actually blood siblings. They were raised together by Garp and consider each other as brothers, so they still count.
Fran and Veronica Madaraki of Franken Fran were outright made to be this. Fran was made to preserve life (which can lead to unpleasant results); Veronica was made to end it (which she prefers to do swiftly and painlessly, though often gratuitiously). Fran tries to put Veronica more on her side of the scale, but so far, no dice.
Fuka and Fumika Narutaki of Mahou Sensei Negima!. The former's the trouble-making class pankster while the latter's constantly worried about how the former's pranks will get them in trouble as she gets dragged along.
Umehito Nekkozawa and his younger sister Kirimi from Ouran High School Host Club. He's dark, brooding and extremely photosensitive, while she's cheerful, outgoing, and hates dark places.
The twins have some of this as well, although only when they are separated. Hikaru keeps the trouble-making personality (with some added Tsundere) whereas Kaoru is much more mature.
Shion and Mion from Higurashi no Naku Koro ni. Shion is more laidback and polite then her tomboyish twin sister. However, it is later seen that Shion is the tomboy, and Mion is the more feminine one. It's complicated.
Only if you make it that way. The character we know as Mion, while originally born as Shion, is still the tomboy and vice versa. It's not as complicated as you think.
Black and White of Tekkon Kinkreet. Black is violent and territorial and White is childish and innocent. The fact that they need each other to balance out the pair is repeated often throughout the film and becomes a plot point.
Minatsu and Mafuyu Shiina in Seitokai no Ichizon. Minatsu is busty, loves sports and isn't afraid to speak her mind. Mafuyu is petite and quiet.
Keroro Gunsou has the Hinata sibings, unassertive bookworm Fuyuki and bossy tomboy Natsumi. Even their names contrast, containing the kanji for "winter" and "summer" respectively.
They're not actually related, but Tengen Toppa Gurren Lagann's Simon and Kamina were definitely designed to fit the trope — Simon is shy, relatively sensible, quiet and intelligent, where Kamina is outgoing, reckless, big-mouthed and something of an idiot. Their respective appearances couldn't be much more different, either; Simon is short (prior to the Timeskip, anyway), pale and skinny with dark purple hair and blue eyes, where Kamina is tall, tan and muscular with bright blue hair and red eyes. Finally, in case all of that wasn't quite unsubtle enough, their names also contrast: Simon's name comes from "shimo", the Japanese word for "below", and Kamina's name comes from "kami", the Japanese word for "above".
Amanchu! has Ai and Makoto, the former being a somewhat violent genki girl in contrast with her meek, thoughtful twin brother.
Suiseiseki and Souseiseki from Rozen Maiden are very much this, both including a Tomboy and Girly Girl relationship, but with several more differing characteristic traits. Where Souseiseki is stoic, Suiseiseki is emotional. Souseiseki is serious and collected, while Suiseiseki is mischievous. Souseiseki believes it is the duty for every doll to participate in the Alice Game regardless of personal attachments, while Suiseiseki strictly opposes the Alice Game due to fear of losing her sisters.
Both leading families of B Gata H Kei have this dynamic. Yamada is an energeticCovert Pervert who has little on her mind but sex. Her younger sister Chika is much more level-headed. Takashi Kosuda is shy but thoughtful, expressing himself through his camera. His older sister Kazuki is outgoing, boyish and shameless within her own house.
Raoh and Toki from Fist of the North Star: one of them is a merciless conqueror and the other is a messianic healer.
Samui of Naruto is stoic, calculating and very serious at all times. On the other hand, her brother Atsui is Hot Blooded, rash and a reckless loudmouth. To drive the point home, their names mean Cold and Hot respectively.
The Sasuke and Itachi dynamic plays with this. As a child, Sasuke strived to be like Itachi to earn recognition, but his brother was always several steps ahead. After the Uchiha massacre, Sasuke tried to distance himself from Itachi and become different from him, even refusing to obtain power in the same way as his brother. However, after Itachi's death, Sasuke drastically changes, becoming driven by hate and revenge against anyone who would stand against him, unlike his brother, who was motivated by love, albeit in a twisted way. Ironically, Sasuke would have ended up very similar to Itachi, had the latter not traumatized him in the way he did.
Future GPX Cyber Formula has Osamu and Asuka Sugo. Osamu is a calm, level-headed individual while Asuka is more energetic and cheerful. Franz Heinel and his younger sister Lisa counts as well.
Unsui and Agon of Eyeshield 21. Unsui is serious, responsible, hard working, and polite. Agon is arrogant, self-centered, sadistic, and lazy.
Masao and Sanae Kouda from Detective Conan look nothing alike. Sanae is a Bishoujo GenreOffice Lady, Masao has a huge case of Face of a Thug. Despite this, the siblings are very close... so when Sanae is killed by Watanuki, a man in debt that she was visiting for work reasons, Masao goes Knight Templar Big Brother and decides to prove it at all costs. Even by robbing a bank and hiding his loot near the man's backyard to force the police dig in so they can find Sanae's corpse.
The Suzuki sisters, too. Older sister Ayako is a soft-spoken and mature Ojou, younger sister Sonoko is an outspoken fashionista.
Infinite Stratos has the Shinonono sisters, Tabane and Houki. The older is very silly, while the younger is very serious.
Kotetsu and Muramasa Kaburagi from Tiger & Bunny. Kotetsu is an impulsive, Hot Blooded, dorky as all hell Ascended Fanboy superhero, whereas Muramasa is his down-to-earth, low key, responsible older brother who runs the family liquor store.
Mobile Suit Gundam has Sayla Mass and Char Aznable. She's a hero, he's a villain. She's loyal to the core, he has Chronic Backstabbing Disorder. She's got a boatload of Ship Tease with Amuro. Hewants Amuro's head on a pike. She doesn't want revenge for their father's death, Char is consumed by the need for it. She's naturally empathetic, Char suffers from Lack of Empathy. The two of them have absolutely nothing in common, and are on opposite sides of the war, yet somehow avoid Cain and Abel.
Charles Xavier and Cain Marko in X-Men. And that's before you get into how they are, respectively, the most mentally powerful and the most physically powerful people in the world...
Xavier also has Cassandra Nova, who literally exists to be his polar opposite in absolutely everything.
Batman's two sons, Tim "Robin" Drake (adopted) and Damian al Ghul (biological), in recent comics. Tim is logical, cool-headed, and always follows Batman's example by never killing, while Damian is rash, violent, and thinks nothing of killing his enemies. They slug it out pretty much every time they meet.
You could extend that to Tim Drake and Nightwing (Dick Grayson). Nightwing can be logical, but he's more hot-tempered and his creation of 'Nightwing' directly extended from him rebelling against Batman. Tim and Dick act like actual brothers though, unlike Damian.
And then there's Dick Grayson and Jason Todd. Apart from the obvious (Dick is a hero, Jason is a villain, or at least a Nineties Anti-Hero), Dick is acrobatic, fairly cheerful for a member of the Batman family, and indepedant from Batman. Whereas Jason relies more on weaponry, is dark and wrathful, and is almost pitifully obsessed with being seen as Batman's son true heir, if not replacing the Dark Knight himself.
The (otherwise unnamed) Two Brothers from Marvel vs. DC - one was the Living Embodiment of the Marvel Multiverse, the other was the Living Embodiment of the DC Multiverse. When they became (re)aware of each others existence, they each decided to destroy the other. They made up in the end, because Status Quo is God (Literally, in this case).
Desire and Despair. Death and Destiny. Destruction and Dream. Delirium and... You know what, it's probably best just to leave it at: "The Endless".
Many examples in ClanDestine. The most prominent example is Jasmine/Cuckoo/KayCera and WalterDestine/Wallop. Then again, when their younger sister Samantha complains about their constant bickering, their father Adam attributes it to them being too alike. In a flashback, we also have Thaddeus and Albert, who seem to get on much better.
According to their Tech Specs Skids and Mudflap are this... with the caveat that they're both quite stupid. Skids merely believes he's the smart one.
A famous example, Mufasa and Scar from The Lion King, who are opposite in every extreme.
Since the reveal that Dr. Evil is Austin Powers brother, they probably qualify.
Ian (Ewan McGregor) and Terry (Colin Farrell) in Woody Allen's Cassandra's Dream. Even just visually, the contrast between the brothers is striking, looking nothing alike axcept for being drop dead gorgeous.
Hotblooded Santino and cold hearted Michael in The Godfather
Happens naturally in Thor between him and Loki. Thor was a Boisterous Bruiser who took in the attention without realizing how self-descructive and reckless he was. Loki was the opposite, being quiet and prefers to use trickery and illusions to fight. Thor's character developments showed that he learned to stop, listen, think and be humble. Loki learning to fight, to take control, assert himself and manipulate others was his development to becoming a villain, completely opposite way of Thor.
In Secondhand Lions, both Hub and Garth are Badass Grandpas who had many adventures in their lives, but in the end, Garth is the more calm, bookish one who could sit back an relax while Hub was looking for adventure and had no trouble beating up five punks after getting out of the hospital.
Literature
Li Han Ch'in and Li Yuan, sons of one of the T'ang Lords in David Wingrove's Chung Kuo
Jake and Tom in Animorphs. One (Jake) is fighting to save the world and one (Tom) is a Controller whose Yeerk is trying to take over the world, though the real Tom is probably more Jake-like.
Discworld: Esme and Lily Weatherwax. Granny Weatherwax is the angry, bitter old woman who always saves the day because she feels she has to since her "good" sister Lily decided she'd rather be the evil one. It's especially frustrating to Esme because Lily isn't even particularly good at being evil.
Princes Peter and Thomas in The Eyes of the Dragon by Stephen King (Peter is fit and raven-haired like their mother while Thomas is chubby and sandy-haired like their father).
Fablehaven has Kendra and Seth Sorenson. Kendra is smart, cautious, and thoughtful, Seth is arrogant, energetic, and brave to the point of stupidity.
Most sibling relationships in Harry Potter follow this to some extent, such as Sirius (hates his pureblood-obsessed family and eventually runs away from home) and Regulus (proud to be part of said family), Bellatrix (fanatically devoted to Voldemort) and Narcissa (secretly terrified of him), et cetera. Also, Harry's mother Lily (a muggleborn witch) and her sister Petunia (who is perfectly normal, thank you very much).
In even greater contrast to Bellatrix and Narcissa is their other sister Andromeda Tonks. Not only did she not become a Death Eater, she married a Muggle-born wizard, produced a daughter who became an Auror, and helps out the Order of the Phoenix, though she's not officially a member herself.
The Izzies from The Merlin Conspiracy by Diana Wynne Jones play with this trope. At any given time, the two girls will take on polar opposite traits, for example one being rude and aggressive while the other is shy and fainting. Then, at random times, they'll switch roles. Twin girls in a magical family where only one can be selected to inherit the family's magic, this is their way of fighting back by making themselves completely indistinguishable.
Elinor - the sense - and Marianne - the sensibility, an archaic word for romanticism, in Sense and Sensibility.
Also in Austen, Pride and Prejudice contrasts intelligent, aware, Elizabeth with her pretty but vain and shallow sisters Kitty and Lydia, who are also compared to Jane, who is beautiful but also extremely sweet and loving, and all of the sisters are compared again with Mary, who is plain, austere and studious, yet stupid.
Persuasion fatures radically different Eliot sisters, Anne being friendly, pleasant, and down-to-earth, and her two sisters being selfish hypochondriacs.
Sansa and Arya Stark in A Song of Ice and Fire. They even look completely different (Sansa is a beautiful redhead like her mother, Arya is longfaced and darkhaired like her father.)
Also, the vicious Joffrey Baratheon and his gentler little brother Tommen.
Also, Stannis and Renly Baratheon.
The twins Jaime and Cersei Lannister seem to be very similar in A Game of Thrones, but when they start getting PoV chapters and character developement in the later books, they move towards this trope. It's particularly in terms of how much morality (and sanity) they retain in any given situation.
Thom and Alanna in Song of the Lioness. Thom likes to do magic but hates swordplay. Alanna, his twin sister, likes swordplay but initially fears and detests her magic.
Leafpool and Squirrelflight in Warrior Cats, especially during The Second Series.
In Ayn Rand's Atlas Shrugged, we have Dagny and James Taggart, and Hank and Philip Rearden. Both sets of siblings hold polarized world views and that in turn shows us that blood is not Thicker Than Water.
Live Action TV
Claire and Lyle, as well as Nathan and Peter, from Heroes.
Hiro and his older sister Kimiko, with Hiro being idealistic, child-like, and bored by the prospect of being a businessman like his father; Kimiko is intelligent, motivated, and ambitious in regards to taking a place within the family's company.
Sam's twin sister Melanie from iCarly. The former is almost permanently grouchy, borderline sociopathic, and sarcastic, while the latter is upbeat, outgoing, and perky.
Aunts Lily and Vivian in Pushing Daisies are both eccentric shut-ins, but the similarities end there.
The Booth brothers from Bones - Booth the elder likes his comfort zone while Booth the younger is flashy and much more upwardly mobile.
The Girls and the Boys from Jon And Kate Plus Eight (the somewhat bossy Girls take after their mother while the more laid-back Boys take after their father)
Megan and Lily in Privileged and, to a lesser extent, Rose and Sage.
Firefly: The Tams. Simon is cooler and calmer and more disciplined, and River is more sensitive and (for obvious reasons) more erratic. On the other hand, she is physically more powerful.
NUMB3RS: Don is more "Jock-like" and Charlie is more "Geek-like".
In the first season of The Big Bang Theory, the twin sister of the gawky, socially awkward nerd Sheldon is revealed to be a gorgeous, statuesque Southern Belle.
Dick and Beaver on Veronica Mars. Dick is loud, stupid, sex-obsessed and borderline-sociopathic. Beaver is quiet, smart, reclusive and actually sociopathic.
From the new BBC Sherlock, the Holmes brothers are portrayed this way. Sherlock is easily bored and implied to have as much predilection for starting crime than stopping it, if the latter was impossible. Mycroft runs a shadowy government agency and is a much calmer and more collected than his dramatic, wild brother. This is in contrast to the characters of the original books, where Sherlock was driven and really cared about what he called "his art," while Mycroft was terminally lazy and probably could have been even greater than his brother, except that he didn't care to be.
Identical twins Katie and Emily Fintch from Skinsat least in their first season. Katie is the leader, dresses like sex-on-legs and Really Gets Around ("I haven't not had a boyfriend since I was seven"). Emily is eternaly in her shadow, dresses slightly more concervative and falls in love and is monogamus. There is also the tiny little fact that Emily is a closeted Lipstick Lesbian and Katie is a raging homophobe whose favorite target is the girl that Emily has fallen for.
Aaron Hotchner from Criminal Minds and his brother, who appears for exactly one episode and is never mentioned again. Perhaps their prominence in the series is another way that they're opposites?
The Otterloop kids in Cul De Sac. Alice is a hyperactive attention seeker. Petey is anxious and quiet.
Tabletop Games
The Unconquered Sun and Luna, from Exalted. One is so absolutely perfect and virtuous that he imposes order on the world by his mere presence, and the other embodies chaos and change to such an extent that she doesn't even have a consistent Motivation. They weren't created at the same time, though, or one could say that they are literallyDifferent as Night and Day.
Urza and Mishra in Magic: The Gathering have a strong Red Oni, Blue Oni dynamic: Urza is detached and introspective, while Mishra is hotheaded and outgoing.
Video Games
Rin and Len Kagamine from the Vocaloid (and Hatsune Mix) series.
Iris and Colonel of Mega Man X are technically identical twins: as a developing single reploid, they couldn't handle the series' thematic Logic Bomb and split into Iris, compassion for all living things and Colonel, the willingness to kill without hesitation to protect and for peace. They were an attempt to replicate the titular X's ability to handle this paradox. They fact they failed to live up to these principles, even one at a time, causing Zero to have to kill Colonel and then a grieving Iris to combine their power, attack Zero, and also have to be killed may have originally foreshadowed that X would eventually no longer be able to handle the Logic Bomb himself - Copy-X of Mega Man Zero was originally intended to be an X who had lost that compassion and reluctance to kill and become a Knight Templar that Zero would have to kill.
Bethany and Carver Hawke from Dragon Age 2 definitely count. Bethany is kind and supportive of Hawke, whereas Carver is surly and shares a rivalry with Hawke.
Yun and Yang from the Street Fighter III series. Yun is loud and outgoing, while Yang is quiet and introverted. Also, Yun focuses on the strength of his attacks, while Yang focuses on the number of hits.
Twin example: Hisui and Kohaku from Tsukihime. Hisui is an introverted maid who is skilled at cleaning, but lousy at cooking. Kohaku is an extroverted maid who is skilled at gardening and cooking, but terrible at cleaning.
Also from the Nasuverse, Shinji and Sakura in Fate/stay night. Subverted in that they're not blood siblings. Sakura and Rin are, though, and also fit this trope. Sakura's powers match her side nicely, to boot.
The three Pegasus sisters are a rare trio example. Quiet, serious Fiora butts heads with boisterous Farina, who in turn gets a kick out of teasing both her and shy, sensitive Florina.
In Fire Emblem 6 we have another sibling trio... also of Pegasus sisters. Yuuno is a sweet Action Mom, Thite is a stoic Defrosting Ice Queen and Thany is a hyper Genki Girl. And there's also a set of twins: the cheerful mage Lugh and the snarky shaman Rai.
Unusual triplet variant, from Metal Gear Solid - Solid and Liquid Snakes are extremely diametrically opposed; reserved, guilty Solid lacks his brother's ambitious, manipulative nature, and passionate, vengeful Liquid lacks his brother's wisdom and emotional clarity. This is complicated by the arrival of the third triplet, the calculating, focused Solidus, who considers himself a 'perfect balance' of his brothers' traits - he's wise and manipulative at once.
The Komeji sisters as well: Satori is usually portrayed as being the calm and possibly deadpan elder sister with hidden emotional depths, while Koishi is usually portrayed as a very lively and cheerful girl who occasionally gets too energetic when hugging Okuu.
It gets better with the Komeijis. If you take an image of either of them and invert the colours, their clothes (and hair... mostly) will take on the colours of the other sister!
Netto (Lan) and Saito (Hub) Hikari AKA MegaMan from Rockman EXE/Mega Man Battle Network, especially in the Japanese version. Netto is outgoing, brash, and rather hot-headed; Saito is more calm and collected.
Hisui and Kohak in Tales of Hearts. The elder is Hot Blooded and impulsive and rude, and even his speech is crass; his sister is soft-spoken and polite. There's also Croaseraph, who is an aggressive Dual WieldingGlass Cannon who wants to Destroy All Humans!, and his brother Crinoseraph, a stoic, defensive spellcaster with two shields who's maintained his loyalty to his master.
DanteandVergil embody this trope, and just about every other antagonistic sibling relationship ever created.
In Apollo Justice: Ace Attorney, Kristoph Gavin is a cool, businesslike defense attorney while his brother Klavier is an wild, extroverted prosecutor. Futhermore, Kristoph is evil and Klavier is good.
Ronny and Sally Dobbs of Backyard Sports. Tony and Angela seem like this, but they're both egotistical.
The Williams sisters from Tekken. Nina is statuesque, cold, and blonde while Anna is the curvaceous and flirty brunette.
Itsuki and Sayo in Suika. Itsuki is gentle, shy and a bit of a pushover. Sayo is brash, slightly tomboyish and aggressive.
Fyuria and Zerva in Record Of Agarest War. Fyuria has light-based attacks, Zerva has darkness-based attacks. Together, they have a powerful Yin Yang Bomb.
Same thing with Lavinia and Faina.
Jeanette and Therese Voerman (AKA Tourette Voerman) from Vampire the masquerade bloodlines. The Malkavian PC even describes them as "The Ivory Princess" and "The Ebony Princess" respectivly.
Subway Bosses Emmet and Ingo of Pokémon Black and White at the very least appear this way; Emmet wears white and is always seen smiling, while Ingo wears black and is constantly frowning.
Dark Souls has the Queen of Sunlight Gwynevere and the Darkmoon God Gwyndolyn.
From the Start of Darkness prequel, Redcloak and Right-Eye also count. Later becomes Cain and Abel.
Oasis and Kusari in Sluggy Freelance. Kusari is emotionless and unfailingly loyal to Hereti-Corp. Oasis is an Ax CrazyYandere who kills all Hereti-Corp employees on sight.
Angelika and Julie from Our Little Adventure. Julie is mature and responsible and Angelika is a nutcase.
Their guardians are also their ectobiological siblings, but the yin-yang shows up most in Rose/Roxy and Dave/Dirk, who are always wondering if their guardians are being ironic/sincere and cruel/playful, respectively.
The Troll kids (who are basically siblings) do this with their ancestors and each other. For example Vriska likes to torture the child-like Tavros and while they're both considered losers their ancestors were a hugely successful pirate queen and an almost-successful messiah-figure.
Carl and Herman too, with Carl's magic and strategy being contrasted by Herman's muscle and brute force. "Dojo Alone" showed that, if they ever worked together, they'd be unstoppable, but they can't stand each other.
Danny and Jazz in Danny Phantom. Danny is insecure, rash and powerful, while Jazz is book-smart, confident and collected.
The Legend of Korra gives us Mako and Bolin - one's a broody, dark, Troubled But Cute firebender; the other's a boisterous, fun-loving earthbender. Mike and Bryan must like this trope.
Yin and Yang from the Histeria! episode "Return to China".
Phineas and Ferb, in some ways, though their differences seem more complementary than opposed, given how close they are. (Technically they're stepbrothers, though even they never refer to themselves that way.)
For that matter, either/both of them with their older sister Candace.
Zack and Wheezi of Dragontales. Not only that, but they are also two halves of a two headed dragon.
Ang and Ling in Legend Of The Dragon. Ang is an easy-going, self-effacing hero, and Ling is an intense, ambitious Anti-Villain (later Anti-Hero). She even gets her powers from "the darkest Yin".
Hank and Dean, the titular Venture Brothers, have grown to become this in later seasons. Dean is a nerdy, frail, non-confrontational Non-Action Guy who is being groomed for a career as a super scientist, while Hank is an underachiever and wannabe Action Hero.
Princess Celestia and Princess Luna in My Little Pony Friendship Is Magic. Celestia, who controls the day, is gentle, motherly, and a bit mischievous, while Luna, who controls the night, is stern, overly formal, and a bit bad-tempered (as seen in "Luna Eclipsed"). That may be a side effect of being sealed in the moon for a thousand years, though.
Real Life
Christopher and Peter Hitchens. Christopher is a very outspoken atheist/anti-theist and holds predominantly (but by no means exclusively) liberal political views. Peter is an Anglican convert from atheism and holds predominantly conservative political views. Granted, both are relatively high-profile journalists, but beyond similar vocations and genetics, the similarities generally end there.
Chris is known for drinking and smoking a lot, whereas Peter can't drink much and doesn't smoke. Plus, Chris supported the Iraq War, bucking the left-wing consensus, whereas Peter opposed it, bucking the... Uncanny.
George W. and Jeb Bush. Both are Republican politicians, true, but George is (by all accounts) a very personable man who parlayed his youthful love for the bottle and a certain white powder into a deeply-held religious faith. Jeb (by all accounts) is somewhat less personable (though not half as detached as their father), and seems not to be half as religious as his brother. Oh, and one is seen as being rather stupid (although some see this as Obfuscating Stupidity), and the other is quite intelligent and certified political whiz.
Not so sure about Jeb not being so religious. He is a high ranking member of the Knights of Columbus.
The Knights of Columbus are Catholic. George W. Bush is a born again Christian. It's a different sort of religious attitude, even if there's an equal level of devotion involved.
The Mitford Sisters. Two of them were Nazis Diana (who married Oswald Mosely, leader of the British Union of Fascists) and Unity (who was a personal friend of Adolf Hitler). Jessica on the other hand was a member of the Communist Party and civil rights activist. Nancy was a novelist, and Deborah is the Dutchess of Devonshire; Nancy was considered to be a moderate socialist, and Deborah a moderate conservative. Pamela was the only non famous sister.
Prim and proper Elizabeth Windsor vs. her sister, Princess Margaret the partygirl. (Both are universally agreed, however, to be infinitely preferable to their uncle David).
