Caya was the name of a pen&paper rpg char of mine, a fighter I rolled up in my late teens and kept playing all through my twenties (our group has since moved on to other worlds, but I don't think she's hung up her sword just cause I'm not around to watch her wield it anymore ). So whenever I started an RPG or MMO on the computer, her name became my default char name. Caya's raised her sword (and the odd lightsaber) against injustice in many, many worlds by now, and I figured she would hold her own among Watson's Warriors . No, seriously, it's just become my to-go name on forums because online friends tend to know me by that name.
About the avatar, I tried to make a suitable one by now, but it's likely to change again - I'm not really satisfied with it, but my photo-editing skills are close to nonexistent.