Grim (Spencer Darthe)

Grim, of course, wasn't always a ferocious, disease-addled beast. Back when he was simply Spencer Darthe, he was your typical moody, confrontational type, preferring to spend his time lurking around Fairfield's various rooftops and alleyways, engaging in parkour and leaving graffiti on every surface. While a fairly talented artist, he lacked the drive or desire to do anything constructive with his skills, and this combined with his frequent run-ins with authorities for vandalism led to a very strained relationship with his family. It was actually pretty rare to find him at home, seeing as it inevitably led to very loud arguments with his parents, and so you were more likely to see him passed out on a bench or on a roof at night out of stubborn refusal to be around them.

It's been theorized that Spencer was actually one of the first to come into contact with the Green Flu virus, although exactly why his body reacted to it so strongly is anybody's guess. At any rate, the animalistic aggression it triggered resulted in him killing his parents with his bare hands, before escaping through a broken window and beginning his life anew as an apex predator (his younger brother Ryan, not home at the time, was spared this gruesome fate; however, his whereabouts are currently unknown).