Red Oni, Blue Oni/Tabletop Games

Examples of in  include:

Board Games

 * Siblings Grave and Jaina Stormborne from the Fantasy Strike universe. Dedicated swordsman with wind powers versus hot-tempered archer with fire powers. Unsurprising, as it's a very deliberate Street Fighter Homage and they're the Ryu and Ken analogues. Designer David Sirlin worked on Street Fighter HD and Puzzle Fighter, and his games Yomi and Puzzle Strike were inspired by those games. but he ended up creating his own setting and characters rather than getting the license.

Tabletop RPG

 * Traveller: Vilani and Zhodani are Blue, Aslan and Vargr are Red. Solimani are sort of in between. The Third Imperium is a very Blue empire, but some of its member worlds are more red.
 * Forgotten Realms:
 * Among the gods of war in the Faerûnian Pantheon, Tempus (supreme war god to whom virtually every combatant on the planet prays to on the eve of battle) and Garagos (god of bloodlust and destruction) are red, and the Red Knight (goddess of strategy and tactics) is blue.

War Games

 * Warhammer 40,000: The loud, bombastic Colour Sergeant Kell versus his Heterosexual Life Partner, the calm, calculating Ursakar "Tactical Genius" Creed.