After all, there are always aspects to an RP character that you don't always have a chance to play out, or may want to expand beyond what has been established. It could also be such a ingrained part of who they are, that it has never been brought up before.
1. Comment, with a list of head canon facts on your character. (Arbitrarily set at 10. More or less is fine.)
2. Rinse, repeat?
3. Questions from other muns are of course, welcome.