Rhianne is revamped from a fanfiction-ish Buffy story I wrote some time back-not sure how great it is, but what the hey. I wanted my own vampire slayer character and thought she would make a great RP character too. Plus she got issues. As lots of characters I'm sure do.
Candace was actually gonna be for a future vampire slayer story that was going to take place in the year 2098 of our world, but I never got around to writing it. If I do, then great, but for now she is solely a roleplay character. And of course, going off the idea that there could only be ONE slayer in the Buffy-verse, that was how it was gonna be. With Candace living years and years later after Rhianne's unfortunate demise at the hands of a demon NPC. So, yeah, I did kill off Rhianne, but I resurrected her for SotE. In this setting, vampire slayers have way more backup and lower mortality rates anyway, so she and Candace are both going to be around for quite some time. If not for-EVA! LOL.
Chandra was initially created for a fantasy rpg that went kaput before I even had a chance to test her out. She is in two settings, this one and a private yahoo group rpg. Not sure if I will bring some of my NWN characters here or not, been debating with myself over that.
And sometimes it may be best to recycle old characters because you would know the old character better than any new character anyway, thus easier to get into their head on what they would think, feel, say, do, etc. But also because there may in fact be such a thing as too many characters (oh my gosh, did I actually type that? :o) But that may end up being the case the more characters that are added to a 'palette' or portfolio.
Sometimes a character is the mixed result of two previous characters, or just aspects of a former one. Many variations can exist.