This is the character builder I used to help me get the basic details down for Anvari – http://www.ashami.com/rpg/
It’s actually pretty snazzy, and useful for both PCs and NPCs – tables to roll on, or just things to pick from. Once I had a basic idea (which for me was just the character motivations) I was able to run with things until I had a character I really think will be fun to play.
Double fun, I’m going to use it to come up with some personality and backstory for my other tiefling (Antha Darkmore, who is a Witch (Pathfinder)). She’s in a much less RP focused group, but having a backstory and a personality is fun. I think I’m going to go with something along the lines of “creepy as fuck” for her basic character template. After all, she does have a spell that lets her vomit spiders. (And one that my group won’t let me take, where you peel off your own skin and turn it into a construct to go do dirty deeds for you. It’s called “skinsend” and it’s horrifyingly awesome.)
Antha is in a campaign that has her hunting for Baba Yaga – it’s pretty spooky, and fairly fun so far.
As a person who usually plays conventional races in unconventional ways, it’s a little odd to be playing two unconventional characters at the same time, but they have such different flavors that I think it’ll work.