Take a look at some of your old SUs. Is there any recurring or overlapping traits that are prevalent in your characters? It could be a name you constantly use, or a certain consistent appearance they have, or a certain personality type? Perhaps something a bit more subtle?
Well, simple question. It's always a sarcastic character for me who enjoys insulting/teasing people a lot. Almost always xD I guess I always put that part in because I'm kinda like that in real life too, and find it easier to relate to such a character d: