Sunshine and Sourwolf

Derek gets hit by a curse that separates his more gentle and happy parts from his darker self. Stiles is quite surprised to find that Derek is, in fact, able to smile, and maybe he's a little bias towards Sunshine. Sourwolf, meanwhile, tries to not feel jealous of himself, because that's just fucking ludicrous and he's not that pathetic. Prompt on Tumblr via Bilesandthesourwolf.