A variant of Odd Couple featuring an older veteran character, and a younger novice. Often the former is a Retired Badass who is somehow rendered powerless (or just helpless against current threats) and has to rely on a newbie, who happened to be around and accidentally shows a lot of promise, so he tutors him.
Perfect setup for Red Oni, Blue Oni - the Hot Blooded younger character is kept in [...] [tvtropes.org]