Red Oni, Blue Oni/Western Animation

"Raph: Teacher's pet! Leo: Ninja dropout!"
 * My Little Pony Friendship Is Magic: Each type of pony has two representatives and each duo provides a clear contrast between them:
 * Earth pony Pinkie Pie is a Genki Filly and a Cloudcuckoolander, compared to Applejack, who is down to earth and more straightforward.
 * Turning to the unicorns, Rarity is prone to theatrics, often descending into drama queen territory, which contrasts with Twilight's serious and somewhat grumpy nature.
 * Meanwhile, the pegasus Rainbow Dash is an extremely confident Tomboy to Fluttershy's shyer and uncertain Girly Girl.
 * All three are exemplified in "Hearth's Warming Eve" where, in a pageant, the reds were cast as their race's leaders while the blues played their Beleaguered Assistants.
 * Other relationships show signs of this; for instance, Applejack is a Blue Oni to the more gung-ho and impulsive Dash, but a Red Oni compared to the prim Rarity.
 * Ironically, despite being the Red Oni in pretty much any pair (except maybe when teamed with Pinkie Pie; that one has been shown going both ways), Rainbow Dash is a blue pony.
 * This is a list of the Mane Cast (and Spike) by order of most red to most blue: P, R, A, S, R, T and F
 * The Cutie Mark Crusaders count as well. Scootaloo being the Red Oni to Sweetie Belle's Blue Oni. Applebloom is generally the Blue Oni to Scootaloo, and can be either the Red Oni or Blue Oni to Sweetie Belle.
 * Also done with the Princesses, though played unexpectedly. Celestia, brightly colored Monarch of the Sun and the Day, is quite clearly the calm, rational, wise Blue Oni, while Luna, dark-colored Monarch of the Moon and the Night, is the short-tempered and emotionally driven Red Oni.
 * Twilight Sparkle, never more than one panic attack away from insanity, is the Red Pony to her brother, the captain of the guard Shinning Armor.
 * My Little Pony as a whole had several of these. The most obvious being Firefly-Medley and Cheerilee-Rarity.
 * Transformers Generation 1. Blaster is loud, outgoing, spontaneous (and red) while Soundwave is quiet, introverted, and calculating (and blue).
 * Jazz (Red) and Prowl (Blue) also count in some continuities, especially in the IDW comics and Transformers Animated.
 * S, the gung-ho backstabber, with T, the more reluctant henchman.
 * Teen Titans has two sets: Robin and Starfire are represented by Red and are more brash, stubborn, and passionate than the others (Starfire displays this most in the comics, to which the flashback/origin episode "Go" paid tribute). Cyborg and Raven are represented by Blue and are more intelligent, analytical, and, in Raven's case, cold.
 * That, when they are in combat, but when they just hang along, Starfire and Beast Boy are more on the Red side, due to the fact that they are almost always happy, laid-back, and carefree, while Raven and Robin have blue traits, being controlled, calm, and down to earth. Cyborg falls in the middle.
 * In the current Teen Titans comic, Red Devil (literally a Red Oni) and the new Blue Beetle have become a comic relief dynamic duo that fans have dubbed Beevil. While both characters have similar personalities, Beetle tends to be level headed while Devil is more impulsive.
 * Don't forget about Thunder (blue) and Lightning (red) from the 4th episode.
 * Slade is definitely the villainous Blue to Robin's heroic Red.
 * Avatar: The Last Airbender has played with the red vs. blue color game quite a bit. Probably the most clear cut case for this in actual characters is the contrast of angry, defiant Determinator Zuko, who lives and dies with the Indy Ploy (although he is by far one of most complex reds), and the Dangerously Genre Savvy Chessmaster/Dragon Azula, who even makes blue fire (which is actually hotter). Some other notable examples of playing with red vs blue include:
 * Zuko's Dream Sequence, where his Uncle Iroh is represented by a red dragon and Azula by a blue one.
 * Zuko also used a visibly different fighting style.
 * Best friends turned enemies Avatar Roku and Firelord Sozin both had dragon companions. Roku's was red, Sozin's blue.
 * Aang is, appropriately enough, a combination of the two. Aang normally can be both foolish and passionate (represented by his normal saffron clothes ). But when in his glowing blue Avatar State, Aang can become frighteningly cold and ruthless, to the point where Aang himself has nightmares about it.
 * Also invoked in the last half of the third season, between Zuko and Katara. Katara is constantly angry and emotional and extremely protective of Aang and her own interests. For once, Zuko is calm instead of passionate and thinks about how to deal with her. Ironic, in the sense that Katara is typically dressed in blue and Zuko in red.
 * Except, of course, in each of their 'spirit' alter-egoes: the Blue Spirit and Katara's reddish Painted Lady. In that commonality, their colour schemes reverse; likewise, in the interactions between just the two of them, they switch roles.
 * Likewise, before, they fit this but with the opposite roles. Originally, Zuko was searching for the avatar, whom no one had seen for a century, as part of a crazy scheme to get back in the good graces of his father (just in time for ). Katara, on the other hand, seemed to be pushing for a long-term strategy of training the avatar and restoring an earlier period of peace and balance.
 * More broadly, this applies to the Fire Nation and Water Tribe. This is especially clear in the Siege of the North - the Fire Nation troops are the aggressive attackers whose arguably deluded military leaders (General Zhao and Prince Zuko) are busy with insane schemes ( and capture the avatar respectively). Meanwhile, the Northern Water Tribe are defending themselves, sometimes with the more planned ( and seek help from the spirit world. The color scheme throughout those episodes fits this trope to a t - the Fire Nation are typically dressed in red (and black) compared to the Water Tribe, who are typically dressed in blue (and white or gray), and even more obviously, the moon and night sky become blood red when, foolishly risking the destruction of the earth in order to prevent water benders from bending, thereby making the city an easy target. The response from the Northern Water Tribe is exceptionally non-aggressive, with the aim of restoring balance to the world and enabling others to fight against Fire Nation imperialism.
 * Also, the (red) Fire Nation and the (green, not blue) Earth Kingdom during and the establishment of Fire Nation colonies, where the Fire Nation are pretty clearly the (unsustainably) aggressive party. Of course, the Earth Kingdom has the Dai Li, who dress in cooler colors and.
 * Also, the elements themselves. Fire and water, anyone? Fire is offensive and water is more defensive.
 * And even earth and air, as in red clay. Earth is offensive and air is definitely defensive.
 * Although, at first, Stan and Kyle from South Park had similar personalities, later on, they were differenced. Stan was an introvert, calm Deadpan Snarker, while Kyle was an impulsive, bold Hot-Blooded Snark Knight, especially in Cartman's presence.
 * Tweek and Craig fit this trope, as well. The former is hyperactive, paranoic, anxious, who shows his emotions easily, while the latter has a darker personality, being stoic, pragmatic, monotonic, and ironic.
 * Possibly unintentional, but Blitzwing of Transformers Animated has a Split Personality represented by his three faces. The black face is The Mad Hatter, but the red and blue faces are textbook red and blue oni: the blue face is cold, calm, and calculating (and uses ice powers), while the red face is brash, impatient, and agressive (and uses a flamethrower).
 * Even his alternate modes reflect this; the blue face wanted to choose a fighter jet, maneuverable and good for attacking from a distance, while the red face insisted on an assault tank, heavily armored and bristling with firepower, ideal for being right in the middle of the action. After they'd argued for a bit, the crazy face stepped in and, cackling madly, scanned both; which one he uses depends on which of him is driving.
 * Interestingly, while you'd expect Jetfire and Jetstorm to follow the trope (they even have red and blue color schemes, respectively), they avert the trope by both acting pretty red. Of course, they are working for Sentinel Prime, so who knows how that affects their personalities.
 * Sentinel Prime is the red who is reckless and an arrogant Jerkass, Optimus Primes is blue, being far more level-headed and humble to everyone. Ironically, Sentinel's primary color is blue, while Optimus is red.
 * Then there's Bumblebee, who's the Kid Appeal Character, and Prowl, who is more mature and more experience in fighting.
 * Swat Kats: Chance 'T-Bone' Furlong and Jake 'Razor' Clawson. And when they're seen outside their vigilante and work clothes, they're wearing their respective colors.
 * Sparx the red monkey and Gibson the blue monkey from Super Robot Monkey Team Hyperforce Go!!.
 * In Justice League, Hawk and Dove, who are also brothers,
 * In Xiaolin Showdownm good examples on the villain side are Jack Spicer (red) and Chase Young (blue).
 * Leonardo (blue) and Raphael (red) in Teenage Mutant Ninja Turtles. Reversal in that Leo is the leader of the team (aside from Splinter). Raph does the Blood Knight bit when he takes the guise of  in the CGI movie.
 * In fact, they pretty much summed up the trope in four words with this exchange from the first episode of the '03 series:
 * In fact, they pretty much summed up the trope in four words with this exchange from the first episode of the '03 series:


 * And those were their first lines in the series!
 * Inverted with Pablo and Tyrone of The Backyardigans: Pablo's blue, hot headed, and panicked a lot in season 1, placing him as the Red Oni. Orange-furred Tyrone, on the other hand, is calmer and more level-headed, which are true aspects of a Blue Oni.
 * In the cartoons series for Disney's Hercules, Ares the God of war and Athena the Goddess of wisdom, who were siblings and rivals, were perfect representations of this trope.
 * Aladdin the Animated Series: Aladdin: red/purple and white, uses his own strength, lives with a mess of friends, has a monkey sidekick, versus Mozenrath: dark blue and black, uses magic, lives pretty much alone in a ghost city, has an eel sidekick.
 * In Taz-Mania the Taz/Dingo shorts, Taz plays the role of the Hot-Blooded red oni while Digeri Dingo plays the role of the cool and cunning blue oni. Also, Molly and Jake, with Molly being the easily-stressed red and Jake being the more cheerful blue.
 * In Bonkers, Bonkers (red) and detectives Lucky Piquel and Miranda (blue).
 * In Invader Zim, Gir seems to show some signs of this trope, though the colors are reversed. The first few seconds when he was active, the episode "Gir goes Crazy and Stuff", and occasionally through-out the series, Gir's colors switch from blue to red and back again. When red, he seems to show the traits of the Blue oni and is intelligent, calm, and eager to serve his master (often saying "Yes my Master!"). When Blue, he acts more like the Red Oni and is wild and over the top, with no control over his own urges or actions.
 * There is also the scene were Zim hypnotises Dib and the scene shows the ground falling apart with Zim in red and Dib in blue. Makes sense, since Zim is known for being impulsive and not thinking before acting, where as Dib is more scientific and logical (if only by a little bit).
 * Corneil (blue) and Bernie (red) from Watch My Chops.
 * Dagget (red oni) from Angry Beavers is highly emotional and prone to Donald Duck-esque rages; stark contrast to his older brother, Norbert (blue oni), who is cool-headed and considers himself suave.
 * Trevor and Aeon from Aeon Flux. Subverted, in that Aeon, despite being a cool, calculating, cause-oriented Blue Oni, is meant to represent chaos and anarchy, whereas Trevor, the vain, arrogant, people-oriented Red Oni, represents order and stability.
 * Out of the stretchy superheroes in Batman the Brave And The Bold, Plastic Man, who wears red, is much more blunt and okay with stealing valuables from the scene of the crime, while Elongated Man, who wears purple (it's a kind of blue) is much more analytical and noble. Plas has a similar dynamic with Batman himself.
 * Likewise, Batman (Blue) and Aquaman (Red), Atom (Blue) and Aquaman (Red), and...heck, anyone and Aquaman.
 * In Titan Maximum, the original Titan Force Five had the Hot-Blooded Palmer and his Lancer Gibbs (they even wear red and blue respectively). However, the fact that Gibbs was the Only Sane Man of the team (as well as Palmer leaving him to die just so he wouldn't miss a hot date) led to Gibbs turning evil in the first episode.
 * Tiana and Charlotte from The Princess and the Frog! They also fit the Tomboy and Girly Girl mold as well, with Charlotte being the loud, over-dramatic, ditzy, spoiled dreamer and Tiana being the quieter, more down-to-earth working girl. Also, one scene has Charlotte in a pink ballgown with Tiana in a (borrowed) blue dress.
 * Tiana and Prince Naveen also fit the description to a T, with Tiana being a Work-A-Holic and Naveen being overly laid back and lazy.
 * The Amazing Chan and The Chan Clan has two examples, one with an inversion in color: sweet-tempered Suzie wears blue while boisterous tomboy Anne has a lot of orange in her outfit, but responsible Henry wears orange while impulsive goofball Stanley wears blue and green.
 * Henry and June in Ka Blam!!: Henry is the red oni (he's energetic, idiotic (not to extreme levels)), while June is the blue oni (cool, cynical, smart). With June, it kind of makes some sense: she does have blue hair, after all.
 * Ironicly, Henry wears a BLUE shirt, where as June has on a RED jacket.
 * In Life with Loopy, Loopy is the red oni (energetic, life-loving) to her older brother Larry's blue oni (inteligent, shy). Oddly enough, the colors of their hair are the opposite (Loopy has blue hair, Larry has red).
 * The Mooninites from Aqua Teen Hunger Force. While they are both still immature jerks, Ignignot is much more level-headed and sarcastic than the vulgar, in-your-face Err.
 * Beavis and Butthead are a borderline case. While both of the boys are active pranksters and neither of them show good judgement, Beavis is Hot-Blooded, brash, irritable, and violent, while Butthead is more laid-back, calmer, and (barely) smarter. Ironically, Beavis wears a blue shirt while Butthead wears red shorts.
 * Two sets of them in Wing Commander Academy: Payback and Archer (the former is a Blood Knight, the latter often hesitating to end another's life) and, to a lesser degree, Maniac and Maverick (Manic is Hot-Blooded, Maverick is by-the-book enough to have earned an Ironic Nickname)
 * Wakfu has this dynamic between Amalia and Evangeline. Amalia is a Rebellious Princess who absconds for little reason other than boredom and brattiness. Meanwhile, Evangeline starts as The Stoic Badass Tyke Bomb with Undying Loyalty to the Sadida royal family. She is all about duty and self denial and doing what's right. But as things go on, they both learn from each other and end up reaching more balanced positions on the matter of responsibility. Amalia learns from the example of Evangeline's courage and commitment, taking up the challenge of living up to her royal responsibilities and defending the Sadida kingdom at its darkest hour. Evangeline, at the same time, learns how to enjoy herself without compromising her duty.
 * Freakazoid and Cosgrove in Freakazoid. In the episode "Two Against Freak", Roddy MacStew fills in as the Red Oni while Freakazoid is in the hospital. They're even - albeit unintentionally - in the right colors: Freakazoid's in red tights and Roddy's kilt is red, while Cosgrove is always in his blue police uniform.
 * Used a bit with the main six in Recess when broken into three groups of two:
 * T.J. as the red oni (Genki, easily excitable) with Vince as the blue oni (cool, sarcastic)
 * Spinelli as the red oni (hot-tempered, tough) with Gretchen as the blue oni (smart, laid back)
 * Mikey as the red oni (outgoing, drama king) with Gus as the blue oni (shy, quiet)
 * Legend of the Dragon has the dragon twins Ling and Ang. You may think from looking at pictures that Ling is the blue Oni and Ang is the red Oni. However, in terms of personalities, Ling is the red Oni and Ang is the blue Oni.
 * Lightning McQueen and Doc Hudson from Cars.
 * Also by Pixar, Russell and Carl from Up.
 * Foster's Home for Imaginary Friends: Bloo (red oni) is obnoxious, self-centered, and rude, while Mac (blue oni) is intelligent, shy, and always wants to do the right thing (most of the time). Ironically, Bloo is well, blue, while Mac wears a red t-shirt.
 * The Revenge Couple on Total Drama, Trent and Courtney. Courtney is a red oni and Trent is a blue oni.
 * Another couple, Gwuncan, also fits for this trope, as Duncan is a red oni, while Gwen is a blue oni.
 * The Avengers Earth's Mightiest Heroes:
 * Outside of battle, red-clad Iron Man often acts more brash and short-tempered than the calm, reflective, and blue-clad Captain America.
 * For most of the first season, The Wasp loves the exciting and beneficial qualities of crimefighting, but her colleague, Ant-Man (whose red costume seems ironic in this case), prefers to confront criminals by talking things out and rehabilitating them. They switch roles during scientific projects, which Ant-Man enjoys more than Wasp does.
 * One of Wasp's friends, red-clad Ms. Marvel, confronts invaders with violence, while Ms. Marvel's blue-skinned alien protector, Captain Mar-Vell, believes in finding peaceful resolutions. Their first appearance, as ordinary Army majors, contained another visual metaphor: Ms. Marvel wore a red scarf, and Captain Mar-Vell (disguised as an earthling) wore a blue suit.
 * The Heroes For Hire include hot-blooded Luke Cage and restrained Iron Fist. Their different temperaments get lampshaded while Iron Fist meditates.
 * Ozzy and Drix has this with a color inversion just like the movie it was based on, mentioned above, with Ozzy as the Red Oni and Drix as the Blue Oni. This is despite Ozzy being blue and Drix being red.
 * In Looney Tunes, Daffy Duck serves as the hot-tempered, overacting, obnoxious red oni to Bugs Bunny, who is a calm, cool, intelligent blue oni.
 * The Dungeons and Dragons cartoon featured Eric as the Jerkass red oni and Hank as the Down to Earth blue oni.
 * Monster Allergy has Elena as the red oni and Zick as the blue oni.
 * Yin Yang Yo! has Yang who is the aggressive red oni who like to go all melee, and Yin who is the calm blue oni who prefers to use magic. Their colors are inverted as Yang is blue, while Yin is pink.