Serif
Serif is Twim's cousin via his mother's sister. Her father is a fire elemental, which is why she's a fire sprite, not an elf. Serif ran away from home to escape her crazy conservative family, and moved in with Twim. Until they find a bigger place, she's stuck sleeping on his dorm's common couch.
Serif is at once the most cynical and yet the most naive of the group; her childhood in Kansas simply didn't expose her to much of the world, though it did teach her skepticism. She seems to be adjusting well to life in the big city, after a few initial difficulties.