I read Reid's app, and OMG I LOVE HIM! I seriously want to give him a hug... even though he'd totally hate me for it.
So, I offer thee Vivianna. It's funny, because I figure that if Viv didn't have her aunt and uncle, this is basically how she'd have turned out. As it is, she's a bit of a mess. It's been hinted at a lot, but Viv basically has a "nice" side, and a "mean" side. She's only ever really "nice" when completely comfortable, and around those she's closest too. When angry, threatened, frustrated, upset, or manipulating, her "mean" side will come out. When feeling neutral, she'll use some sort of combination. She doesn't have multiple personalities disorder or anything, but is just a product of her environment.
She's like Reid in that it doesn't matter if a spell is dark or light, and she has broken the law. I think interaction between the two of them could be potentially brilliant, and could go any direction. Friendship (just because it's nice to have someone that can sorta keep up with you), Rivalry (from feeling threatened, or spawned from something potions-related), or Love (because, power-couple much?).
So, I might have rambled a bit... Thoughts?