History RedOniBlueOni / WesternAnimation

** Brittany is impulsive and emotional (and wearing [[PinkMeansFeminine something pink and girly]]), a [[{{Foil}} contrast]] to Jeanette's calm and scientific mindset (and practical blue clothing).

** Stylistic episodes, two-parted third season finales: "[[Recap/StarVsTheForcesOfEvilS3E37Divide Divine]]" (blue, When Moon goes missing, Star tries to track her down while Marco and his friends deal with the rampaging Meteora) and "[[Recap/StarVsTheForcesOfEvilS3E38Conquer Conquer]]" (red, Star is seemingly the only one left who can stop Meteora from destroying Mewni).

* ''WesternAnimation/StarVsTheForcesOfEvil'':
** Star's energetic and wild Red Oni to Marco's safety-minded and level-headed Blue Oni.

* The ''WesternAnimation/DungeonsAndDragons'' cartoon features Eric as the red oni and Hank as the blue oni.

** On the Separatist side, Count Dooku was definitely the stern, refined Blue to General Grievous's short-tempered Red.
** Jedi Apprentice Ahsoka is also the Red to [[spoiler: Former]] Assassin Asajj Ventress's Blue. Ahsoka generally being the naive learner, taking on many of [[StudentAndMasterTeam Anakin's traits]]. While Ventress took on more of Dooku's traits, despite not officially being a Sith.

* ''WesternAnimation/SWATKats'': Chance 'T-Bone' Furlong and Jake 'Razor' Clawson. T-Bone is the Red Oni because he is the more aggressive type when it comes to his piloting skills in the air, and physical when it comes to fighting on the ground, while Razor is the Blue Oni, being the gadgeteer of the team who also serves as T-Bone's RIO (Radar Intercept Officer) when flying in the Turbokat. Then they're seen outside their vigilante and work clothes, they're wearing their respective colors.

* ''WesternAnimation/BobsBurgers'', [[FantasyForbiddingFather Bob]] (blue) is the somber, mostly calm and hardworking Dad. While Linda (red) is the optimistic, quirky and sensitive [[GenkiGirl Mom]].

** Thirty-Thirty is red oni because he is short tempered and willing get into a fight.

* Dagget (red oni) from ''WesternAnimation/TheAngryBeavers'' is highly emotional and prone to DonaldDuck-esque rages; stark contrast to his older brother, Norbert (blue oni), who is cool-headed and considers himself suave.

** Gumball's mother, Nicole is very ill-tempered, mature and strict, while Richard, Gumball's father, is laid-back and calm.

* In ''WesternAnimation/RegularShow'', Mordecai (blue) and Margaret (red) deliberately follow this trope -- both in appearance and personality. To a lesser extent, there's the relationships between Mordecai and Rigby, and the relationship between Muscle Man and High Five Ghost.

* ''WesternAnimation/AroundTheWorldWithWillyFog'': The excitable Rigodon and the mischievous Tico are red to the blue of the stoical Fog and the serene Romy.

*** The Siege of the North -- the Fire Nation troops are the aggressive attackers whose deluded military leaders (General Zhao and Prince Zuko) are busy with insane schemes ([[spoiler:to kill the Moon spirit]] and capture the avatar respectively). Meanwhile, the Northern Water Tribe are defending themselves, planning to infiltrate the Fire Nation navy]] and seek help from the spirit world. The color scheme throughout those episodes fits this trope to a t -- the moon and night sky become blood red when [[spoiler:the Fire Nation Admiral Zhao begins to kill the Moon Spirit]], 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, [[spoiler:as the princess, something of an incarnate of the Moon Spirit, sacrifices her mortal life]] with the aim of restoring balance to the world and enabling others to fight against Fire Nation imperialism.

** In Season 2, Varrick and his quiet assistant Zhu Li played very straightly. Also Desna and Eska count, Eska becomes a rather terrifying Red (matching or even more scarier than Azula), while Desna plays a submissive and somewhat more understanding Blue twin.

* In ''WesternAnimation/OverTheGardenWall'' Older brother Wirt is an angsty, intellectual, chronic overthinker while his younger brother Greg is a loud, excitable doer.

*** Zuko and Katara in general Zuko is angry and passionate while Katara is caring and nurturing, however in the interactions between just the two of them, they switch roles. Katara is constantly angry and emotional and extremely protective of Aang and her own interests. Zuko is calm and thinks about how to deal with her. Katara is typically dressed in blue and Zuko in red.

*** The Siege of the North -- the Fire Nation troops are the aggressive attackers whose deluded military leaders (General Zhao and Prince Zuko) are busy with insane schemes ([[spoiler:to kill the Moon spirit]] and capture the avatar respectively). Meanwhile, the Northern Water Tribe are defending themselves, planning to infiltrate the Fire Nation navy]] and seek help from the spirit world. The color scheme throughout those episodes fits this trope to a t - the moon and night sky become blood red when [[spoiler:the Fire Nation Admiral Zhao begins to kill the Moon Spirit]], 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, [[spoiler:as the princess, something of an incarnate of the Moon Spirit, sacrifices her mortal life]] with the aim of restoring balance to the world and enabling others to fight against Fire Nation imperialism.

** In season 2, Varrick and his quiet assistant Zhu Li played very straightly. Also Desna and Eska count, Eska becomes a rather terrifying Red (matching or even more scarier than Azula), while Desna plays a submissive and somewhat more understanding Blue twin.

* Inverted with Pablo and Tyrone of ''WesternAnimation/TheBackyardigans'': 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.

** Played with slightly in season 2, where Phil's a bit more emotional.

** [[TomboyAndGirlyGirl Ruby and Sapphire]], the two Gems who [[spoiler:fuse into Garnet]]. When forcibly separated and put into different prisons, Ruby is angry and nerve-wracked, going around screaming Sapphire's name as soon as she's freed; Sapphire, in contrast, calmly sings her in cell, and uses her freedom to [[SuperSpeed quickly]] and efficiently hunt Ruby down so that they can [[spoiler:fuse again]]. This extends to PersonalityPowers in "Keystone Motel", as the pair respectively become very hot and very cold -- [[PlayingWithFire quite]] [[AnIcePerson literally]] - when they're angry at each other. Keystone Motel also lets us get to know them better -- Ruby's emotions are very much worn on her sleeve while Sapphire is outright TheSpock. [[spoiler:Believe it or not, their roles are reversed in "Now We're Only Falling Apart", as Sapphire (red) is absolutely ''[[BrokenPedestal livid]]'' at the revelation that Rose [[TwoAliasesOneCharacter is]] Pink Diamond, whereas Ruby (blue) takes the revelation [[EasilyForgiven quite well]].]]

* Both played straight and inverted on ''WesternAnimation/{{Rupert}}'': The protagonist Rupert Bear wears red and is an adventure-loving thrill seeker whos' always eager to swing into action and come up with an IndyPloy to save the day; his [[TheLancer Lancer]] Bill Badger wears blue, is far more cynical and snarky, and is reluctantly dragged along on all the hero's adventures. In a twist, Rupert is definitely the more level-headed one, while Bill is more reckless and prone to acting without thinking. Whichever you look at it, the two are opposites... [[OddFriendship and best friends]].

* Tommy and Chuckie from ''WesternAnimation/{{Rugrats}}'' are respectively Red and Blue.