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 FighterHomage 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.
Warhammer has the High Elven twins Prince Tyrion (red) and the archmage Teclis (blue).
...and both settings include the Greenskin gods Gork and Mork. One is a god of cunning brutality who will hit you when you aren't looking, the other is brutally cunning and will hit you really hard even if you are. The argument over which is which provides another excuse for Greenskins to kill time bykilling each other.
You also have Leman Russ, primarch of the viking-esque Space Wolves, and Lion El'Jonson, primarch of the scholarly Dark Angels. They were close friends despite their differences, though their respective chapters tend to forget that and only focus on the differences.
Tzeentch and Khorne - Tzeentch is all about magic and planning stuff; he and all his daemons are primarily blue. Khorne is all about hitting stuff in the face without any planning, and he and all his daemons are primarily red. Same goes for Magnus and Angron and their respective chaos marine followers. (Ironically, Magnus's Thousand Sons sported red when they were loyalists and switch to blue after going to the dark side, while the World Eaters started with white and blue before they decided to stop washing their armor. Magnus himself however, remains red in title and color, despite being a blue oni at heart and serving a daemon god that is also primarily blue.)
Angron and Kharn. Kharn was the equerry of Angron, and tried to calm Angron's fits of anger as much as possible. Kharn also crushed the back of two legions, World Eaters, his own legion and Emperor's Children at Battle of Skalathrax, because they sought safe zones under sub-zero weather that froze power armor. Swell guy, isn't he? Now, just imagine how Angron was...
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.
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.