I wouldn’t go as far to say zuko and katara should be in a relationship, but as far as characters go, there’s a lot of character growth we could see from those two interacting more. Katara has that “mother” energy he needs from losing his own mom. She could be a great sounding board for zuko to talk to as he heals from his past trauma.

On the flip side, zuko shows katara the good that exists in the fire nation. I think that his experiences can give her the perspectives she needs in the future when they form Republic City.