Chip seems like the perfect friend to Tabby throughout the season, but almost too perfect. He never gets annoyed with Tabby, even when she only agrees to go to the dance with him if he helps her embarrass Karen in front of the whole school or when she straight-up calls him a bozo for his taste in horror movies. His unrequited feelings for Tabby would also play into why "A" killed Tyler after his fight with Tabby at the Halloween party.
Additionally, he sets his sights on Imogen beginning in episode seven. He shows up at the exact moment her fake baby for their school assignment goes missing to help her find it (and it conveniently has a message from "A" tacked onto it when they do). Then, he enthusiastically pretends to be the father of her baby when he tags along with her to see a social worker about the possibility of giving her child up for adoption.
The identity of Imogen's baby's father is a mystery until the final episodes of the season, and considering she was attacked in a way that was similar to her best friend Tabby, it seemed like there was a chance something even more duplicitous was going on under the surface.
In the end, it's revealed Chip is, indeed, Imogen and Tabby's attacker and Imogen's baby's father. Despite him being a totally sick and disturbed individual, he has nothing to do with "A" and their plot for revenge.
