Chance Alfridge is the most popular boy in Niamh's class at Teras High School. It's not hard to see why: he's friendly and outgoing, he's athletic as well as reasonably intelligent, and he's involved in just about everything. Besides, even if he couldn't necessarily be called attractive by human standards, the other monsters seem to think he's good looking. Melodica Bing, in particular, makes constant attempts to win his affection, but to his credit he sees through her manipulation and has no evident interest in her. Melodica, characteristically, often decides to blame her failure to woo Chance on Niamh, even though he doesn't seem to have any interest in her either. (Not that his disinterest bothers Niamh, given that it's entirely mutual; as a weird three-eyed, tentacled, quadrupedal monster, he's not exactly her type.)
Chance has two heads, one that bears his eyes and another with his mouth. Neither head is physically attached to his body, and he usually carries them around by their hair. While he's pretty good about keeping track of his heads, he sometimes does lose one (or, rarely, both), which poses him a considerable inconvenience until he manages to find it again.