Will first discovered he was a were around the time he turned 15. Due to his mother being killed by a were-beast of some kind when he was just a little boy, and despite the fact that he turns into a fluffy (if alarmingly large) kitty, this messed him up pretty badly. Combined with him not really getting along with his dad, which was probably at least partially also because of his werecat-ness, this led him to run away from home not long after he realized what he was. Helen Magnus, who had both saved him from the were-beast when he was a child and had kept an eye on him ever since, was quick to all-but-literally swoop in and invite him to stay at her Sanctuary in town.

During his time in the Sanctuary, Will met and had a brief relationship with Foster when they were both teenagers. It helped him get some stuff figured out, and they parted amicably.

These days, Will is Helen's second in command while also going to college part time online, with Helen's encouragement. He also spends a lot of time dealing with Zim, who lives in the basement.