86 has this dynamic between the male and female leads of the series, Shin and Lena. Shin is a man of few words who has seen hundreds of comrades die in five years of fighting on the battlefield and is quietly obsessed with finding and killing the Legion personality copy of his brother Rei, whose last memory he has of him is of Rei attempting to strangle him to death when they were children. Meanwhile, Lena is a Nice Girl who is truly trying to make a difference despite being part of the malicious authoritarian government that has abused Shin and the other Eighty-Six, and her genuine empathy and eventual love gives him a reason to live on after he kills Rei. In fact, the special ending song for the first season's Recap Episode is rather on the nose about this with its lyrics:
If I can heal the conflict that's within
I'll know the war has reached its bitter end
In After War Gundam X, Sala Tyrrell wants to become the Gentle Girl to Jamil Neate's Brooding Older Man. Badly. It takes her almost the whole series to succeed.
Kaoru Hanabishi and Aoi Sakuraba from Ai Yori Aoshi. Kaoru isn't as brooding as other Brooding Boys, but he has serious emotional traumas from the abuse he suffered from his grandfather and the death of his beloved mother. Aoi's kind and loving personality helps heal Kaoru's mental and emotional damage.
Akuma no Riddle's Tokaku and Haru are a textbook girl/girl case. The same appears to be true of Chitaru and Hitsugi at first...
Flashbacks reveal that Uryuu Ishida's parents, Ryuuken Ishida and Kanae Katagiri, were this trope to the very letter. The flashback is ostensibly about Isshin and Masaki'sMeet Cute story but includes Ryuuken and Kanae as the Beta Couple. It reveals he was torn between his personal desires and his family duty, and she was hiding feelings for a boy she believed unattainable.
For most of the series, Ichigo Kurosaki was a scowling young man who harbors great guilt whenever he can't protect anyone, while Orihime Inoue remained mostly upbeat and hopeful. It was Orihime, in fact, who came up with the idea of rescuing Rukia after she was taken away by the Shinigami, with Ichigo agreeing and immediately thanking her for it. And when Orihime herself was first injured and then kidnapped by the Arrancar, Ichigo was immensely troubled by her being in pain for it, before he and their friends decided to help her too. At the end of the series, they're revealed to be Happily Married (with a son).
Cross Ange: Ange and Tusk are a gender-inverted example. After she becomes a Broken Bird during the first episodes, he's one of the few people capable of bringing out her nicer side with his kindness, and this eventually leads her to fall in love with him.
Keeping their relationship from the second game (even though it chronologically occurs later), Hajime Hinata and Chiaki Nanami. Once again, Hajime broods a lot about his inferiority issues, and once again Chiaki is a sweet gamer girl who tries to keep his spirits up. Then deconstructed as he feels his emotional reliance on her and his own lack of talent make him unworthy of her love, and he sets out to "become worthy", signing up for a project that completely destroys his personality and replaces it with a new one. Chiaki's left waiting for months, wondering why he abandoned her; when he does return he's even more brooding than usual and doesn't recognize her at all. She still recognizes him, though, and tries to help him again and gets killed because of it, her last words expressing how much she wants Hajime to return to her side.
Also keeping their relationship from the game, Makoto Naegi and Kyouko Kirigiri. However, rather than being just a Gender Flip as it was then, their dynamic is played a bit more straight when Makoto has a moment of broodiness and fear, and Kyouko is the one to lift him up. They're this close to becoming Star-Crossed Lovers, but ultimately survive.
girl/girl version with Rei "Saint Juste" Asaka as the Brooding Bifauxnen and Nanako Misonoo as the Gentle Yamato Nadeshiko-in-training Girl. However, Rei either kills herself or dies in an accident depending on the version.
Mariko Shinobu and Nanako fit in fairly well too, given that Mariko is a Hot-BloodedBroken Bird with severe issues and clings desperately to Nanako, whom she sees as the first real friend she's made in her whole life.
The main couple of Devils' Line, Yuuki Anzai and Tsukasa Taira, could be considered as this. Tsukasa is a nice and innocent girl to serve as Anzai's brooding and aloof demeanor. Needless to say, as the story went by, the two start to fall for each other.
Vegeta and Bulma from Dragon Ball are one such couple. Vegeta is the prince of a once thriving warrior race rendered functionally extinct by Frieza. Vegeta spent his early life slaughtering countless people begrudgingly for the same person responsible for the genocide of the Saiyans. Bulma by contrast is a scientist who has been involved in various adventures with Goku (who is later revealed to be another survivor of the Saiyan race) seeking the eponymous dragon balls and also countering other threats. Though, Bulma isn't exactly gentle, but they do eventually become a couple.
Pictured in the main page image: Kiritsugu Emiya and Irisviel "Iri" von Eizenbern in Fate/Zero. Their marriage was pretty happy until the Holy Grail War happened. Their contrasts had little, if anything, to do with their tragic ending.
Kyo and Tohru. Kyo is a deeply traumatized and angry guy who has been ostracized by his family his entire life. Tohru is an All-Loving Hero who acts as the main healing force for the emotionally scarred Sohmas, including Kyo. Interestingly, Kyo turns out to be the only one who can tell Tohru has fears and insecurities of her own and helps her work through them, making their relationship one of mutual support.
Gender-inverted version: Shiki Ryougi and Mikiya Kokutou from The Garden of Sinners. Shiki is, to say the least, highly brooding and unstable, but Mikiya is incredibly kind and patient with her despite her initial attempts to push him away (that included trying to stab him with a knife). It's Mikiya's presence that keeps Shiki from becoming a complete psychopath.
Inuyasha: Inuyasha and Kikyo would have been this, and sure enough she did manage to "plant the seeds" via teaching him the warmth of the human heart with her kindness. Unfortunately, they were turned against each other thanks to Naraku's deception, making any healing Kikyo managed to do to Inuyasha's wounded heart meaningless. Inuyasha and Kagome, on the other hand, play it straight (Belligerent Sexual Tension notwithstanding), as Kagome helps Inuyasha recover from his wounds and insecurities and goes so far as to completely accept him for who he is, with Inuaysha eventually realising she's the sole reason he's no longer lonely or unhappy. Kaede and the resurrected Kikyo discuss this, with the latter lamenting that she would have been the Gentle Girl had she not died.
Sometimes it is heavily implied in The Irregular at Magic High School with siblings of Tatsuya Shiba and Miyuki Shiba as a kind of Brother–Sister Incest option. While Tatsuya is a cold, emotionless, and cynical Anti-Hero, Miyuki is a pure, innocent, and kind girl, which is his meaning of life as literally the only important person in his life. And yes, she is in love with him. Thus, despite some aspects of his dubious and cynical worldview, it is Miyuki that becomes his life guide and the ground for positive motivation.
A bit of a played with example in JoJo's Bizarre Adventure: JoJolion with Josuke Higashikata and Yasuho Hirose. Josuke suffers a bit of angst from being an Amnesiac Hero, and Yasuho serves to be his Morality Pet love interest. The key thing to note, though, is that both of them are massivecloudcuckoolanders, so it's nearly impossible for JoJolion to play this trope straight.
In K, there is Suoh Mikoto and TotsukaTatara as a male/male version. Totsuka is the only one able to contain and aid Mikoto in regards to his Person of Mass Destruction. May or may not have been platonic (Word of God claims they had a "special relationship" that was kept a secret because otherwise it would be considered "unmanly" in their gang, but does not go beyond that) but it definitely ends tragically. Tatara being murdered is what kicks off the plot and Mikoto dies a mere twelve days later via Suicide by Cop after avenging his death.
Inverted in Kaguya-sama: Love Is War. If you strip away all the mind games, Kaguya's story is ultimately one of how she was emotionally scarred by the environment she grew up in and how falling in love with Shirogane helped her find happiness in life.
Inverted in Kimagure Orange Road, with Madoka Ayukawa as a Broken Bird Brooder who has been rejected by almost anyone outside her family and is believed to be a delinquent, and Kyosuke as the Gentle Ridiculously Average Guy who is rather dim sometimes but still approaches Madoka when almost no one else did. Kyōsuke and his family are (besides Hikaru and Yūsaku) the only ones who understand that Madoka is a good person, and how, she's just troubled and misunderstood.
Adonis and Doroka from Kingdoms of Ruin. Adonis is a violent, aloof young man filled with hatred toward all humans and wishes to wipe them out for their horrible deeds, especially murdering his mentor and mother figure Chloe. However, the witch, Doroka, is a naive, kind-hearted, cheerful, caring girl who wants witches and humans to make peace with each other. Despite their opposite view of things, the two learn to cooperative and bond with each other.
In Magi: Labyrinth of Magic, the dynamics between Aladdin's parentsSolomon and Sheba manage to mix this and Savvy Guy, Energetic Girl. The Brooding/Gentle part comes from post!Character Development Sheba realizing that Solomon is really broken from the alienation he has always had throughout his life, then deciding to be supportive for him and becoming the only one that decides to be his equal rather than his follower.
Rei Kiriyama and Hinata Kawamoto from March Comes in Like a Lion form this kind of pair whenever they're together and have meaningful one-to-one interaction. Rei has a morose disposition most of the time due to many of the issues he deals with. Hina is cheerful and, while excitable at times, is assertive but gentle and non-forceful in her attempts to get Rei to open up and spend more time with her and her family. However, unlike most examples there are no blatantly obvious romantic overtones in their relationship.
In Marmalade Boy, while Yuu and Miki normally tend to go far more by Savvy Guy, Energetic Girl, it turns out that Yuu is extremely prone to depression at times and specially when it's revealed that his father Youji may not his biological dad. When this happens, Miki attempts to comfort and understand his reasons so she can help him out, plus gives him more than one Cooldown Hug; sometimes it works well, sometimes it doesn't.
Menhera-chan: Gender flipped with Momoka and Ougi. Momoka is a depressed Magical Girl with a Dark and Troubled Past while Ougi is a shy and sensitive boy who falls in love with her after seeing her fight as Menhera Pink. He loves her for having an inner strength he believes he does not possess, while she gradually falls in love with him for his consistent support of her even in her worst moments.
Heero and Relena, since Relena helped Heero re-discover the humanity he thought of as lost.
Also a popular view of Trowa and Quatre, with Quatre as a mix of both Brooding and Gentle and Trowa as a tight-lipped but very warm-hearted Gentle Guy.
My Dress-Up Darling: Played with, as both the main protagonists are nice and kind-hearted individuals, but they still have this dynamic. Marin is a cheerful and friendly Genki Girl, while Gojo is a brooding, melancholic and introverted Shrinking Violet.
The manga The Name of the Flower, lives off this trope. The 'brooding boy' is Kei Mizushima, a famous writer of depressing, nihilistic works, who himself has a tragic past and struggles with mental illness. The 'gentle girl' is Chouko Mizushima, the distant relative he takes in after her parents die in a car accident, who grows flowers in his yard, is quiet, soft-spoken, and kind, and in love with him. The story revolves around Chouko's desire to love and save him from his depression and Kei's feeling that he doesn't deserve it, or can never bring himself out of it enough to do anything but drag her down with him.
Downplayed with Naruto and Hinata. Naruto is the near epitome of Determinator, Magnetic Hero, and The Heart—he's the one who usually brings someone else out of their brooding self-loathing attitude. However, during the moments that have even him reach the Despair Event Horizon, it has always been Hinata (the girl who was initially very self-deprecating of herself) who gives him the strength to gain back his confidence. Such moments include Hinata encouraging Naruto right before his fight against Neji in Chapter 98, and then Hinata slapping sense into Naruto when he almost gives in to Obito's Breaking Lecture following Neji's Heroic Sacrifice in Chapter 615.
Sasuke and Sakura fit the description of this trope. He is a gloomy and brooding antihero, she is a sweet and gentle girl with a cheerful character.
In the shoujo manga Niehime to Kemono no Ou (The Sacrifice Princess and the King of Beasts), the initially unnamed King is a brooding and very feared beast with a Dark and Troubled Past and human heritage who has been offered 99 girls as virgin sacrifices, but he always secretly lets them go so they can rebuild their lives elsewhere. The ninety-ninth girl, Saliphie, touches his heart with her kindness and her lack of fear of him and the idea of being sacrificed to him, which impresses him enough to have her taken in as his consort instead.
Gender inverted in Freezing with Satellizer and Kazuya. Eventually played straight, gender-wise, later in the story, when Kazuya starts brooding over some traumatic revelations about his family and Satellizer needs to comfort him.
In the flashbacks describing the Birth of Nerv, Gendo was introduced as a Jerkass failure in life who kept getting into trouble. For example, when Fuyutsuki first met him, it was to bail him out of jail, as Gendo was a recluse and habitual drunk with a penchant for getting into bar fights. Fuyutsuki could not comprehend why such a beautiful genius as Yui would be paired with a failure in life. Gendo then said that he was used to being hated by everybody else. He needed Yui as a philosopher to teach him how to live and socialize like every other human being. As a result, after Yui sacrificed herself to be absorbed in Eva-01, Gendo became The Stoic whose only purpose is to bring her back from the dead.
If you like your Ho Yay, then Shinji can be seen as having these dynamics with Kaworu Nagisa too. Again, this is Evangelion… and it doesn't end well either.
Puppy Love version: Masaru Yada and Hazuki Fujiwara from Ojamajo Doremi. Ever since the start of the series, Hazuki refused to see Masaru as the delinquent that others thought he was…
In Private Actress, the lead character Shiho once was the Gentle Girl to a Brooding Boy named Naoya Koshiba, who was both her first "client" as a P.A. and her First Love. Until Naoya died.
Pokémon the Series: XY: Alain, a brooding edgy teenager, has as his only human companion a bright and bubbly girl named Mairin.
Homura Akemi and Madoka Kaname are both girls, but otherwise fit this trope to a T. Homura is a stoic, highly troubled Byronic HeroineBroken Bird, while the Messianic Archetype Madoka is a kind-hearted and innocent All-Loving Hero. Madoka is the only one able to get close to Homura and get her to express her deeply buried emotions, and Madoka's kindness is the source of Homura's devotion to her.
Deconstructed in the Rebellion movie: Homura loves Madoka so much, and is so desperate to keep her alive after having lost her so many times, that she goes offthe deep end and imprisons Madoka and everyone else in the entire universe in a Lotus-Eater Machine. Twice.
Sayaka Miki wants to be the Gentle Girl to Kyousuke Kamijou's Brooding Boy really, really badly. Considering the Crapsaccharine World that these two, Madoka, Homura, and others live in, and how Sayaka is a deconstruction of tropes like this one, it really doesn't end well.
Re:Zero: Zigzagged. Subaru typically isn't the type to brood and goes out of his way to be energetic and encouraging to the people around him. But when the pain and trauma from his numerous deaths from failed loops threaten to crush his spirit, he specifically desires Rem to comfort him but it's because he knows she wouldn't let him continue to brood and would get him back on his feet to move forward.
The Rising of the Shield Hero: Naofumi and Raphtalia, respectively. In a world where almost everyone treats him like a despicable criminal (at least at first), Raphtalia is the one person who is always there for Naofumi to comfort him with kind words. Even on the rare occasions where Naofumi returns the favour, he does so by reminding Raphtalia of everything she's done for him.
Sailor Moon: Mamoru and Usagi, specifically in the R movie. Mamoru's an orphan who was comforted by a very young Usagi in the hospital after his parents' deaths. Ten years later, they reunite and mimic the same pose of her with her head on his knee comforting him. They normally fit more into Savvy Guy, Energetic Girl, however.
They fit this dynamic better in the manga (unsurprising considering it was shojo) and Crystal. Here brooding is a regular trait of Mamoru's and he's a quiet, sensitive introvert who often ponders if he's good or strong enough to be with someone as powerful as Usagi, who's perky but very kind, caring, and understanding. In Dream, these notions are put to rest which pretty much solves all of their relationship troubles.
Souma Saiki and Masataka Tagami from Sakura Gari are a male/male version. Souma may not look like a brooder, but in truth, he's got MASSIVE issues due to his horrifying Dark and Troubled Past, and one of the biggest reasons why he's attracted to Masataka is his gentle, frank approach to him, offering a contrast with how everyone else is obsessively possessive of Souma himself. And then, shit starts going down for both of them.
Sensual Phrase: Sakuya is the handsome but aloof with the dark past and Aine is the innocent and sweet ordinary girl who can calm him down.
Simoun's Dominura and Limone have elements of a girl/girl version of this from the start, but they really fall into the pattern after their Emerald Ri Maajon. Neviril and Aaeru/Aer are a mixed example — Aaeru is more energetic than the average Gentle Girl, but Neviril is verybrooding.
SPY×FAMILY has this with the fake married couple, Loid and Yor. Loid is the cool but brooding and reserved husband who's also a secretive spy while Yor is the sweet and gentle wife who just so happens to be deadly assassin.
Strawberry Panic!'s Shizuma and Nagisa. Shizuma acts flamboyant to hide her brooding, but when it comes to the surface, boy howdy.
Voltes V: Played With. Heinel is closed-off to anyone not in his circle, and speaks to his fellow Boazanians with a grandiose aura. Katherine shares the Upper-Class Twit attitude most Boazanians have, but she's a friendlier and open person than him and even changes her mind about the war later on.
Your Lie in April has Kousei as the sad and lonely brooding boy, and Kaori as the wild and cheerful gentle girl.
Priest Seto, the preincarnation of SetoKaiba whose life pretty much sucked just as much the first time around, and the white-haired Mystical Waif Kisara.
"Yami Yugi" and Anzu/Tea. Their "date" consisted of large amounts of Yami brooding over his mysterious past/mysterious destiny and Tea trying to cheer him up via talking to him or taking him to arcades before going to the museum.
Yu-Gi-Oh! GX gives out the Ho Yay version of this near the end of season 4 with Yusuke as the brooding guy and Fubuki as the gentle guy. In the final confrontation against Darkness-possessed Yusuke, he rants about how lonely he was, and for not noticing what his best friend feels, Fubuki apologizes and he gently said he will patiently wait for Yusuke to completely opened up to him and become friends again, and chance for Yusuke to be forgiven will always be open for him. He did even said if Yusuke doesn't want to come back to the living world, he will come to shadow dimension as well.
that was kept a secret because otherwise it would be considered "unmanly" in their gang, but does not go beyond that) but it definitely ends tragically. Tatara being murdered is what kicks off the plot and Mikoto dies a mere twelve days later via Suicide by Cop after avenging his death.