"Zuko's mother, who is also my girlfriend's mother, and this could only get more awkward if my mom turned up as well. Or Katara."

In short, you should totally write that.

I'm almost 3000 words into the Getting Together Story. It's at the stage of, "Sleeping with Zuko's sister is the worst idea I've ever had. She probably kills and eats you after sex. Much better to fight with her."