I think it'd be interesting to have her be Zenith's former arch-enemy. I'm not having players roleplay villains right at this time but it is something that would be possible later in the series. Or you could have her go full on NPC villain if you really don't have the time. I like the idea of a psychic character in addition to a Super-Serum. Perhaps a government experiment that went horribly right? It's an interesting concept in any case. 

Also four accepted characters! We're in good shape.