I'm allowing fire benders, earth benders, and water benders. It might be a little unlikely in canon but otherwise it would be too restrictive. The characters I want to use are a waterbender and firebender but I've written their backstory so it makes sense in the story, so I figure as long as it makes sense then it's fine


(And making sense is just like "my waterbender left the northern water tribe" or "my firebender didn't agree with the war so they left the fire nation")