Before Randy, Keith, and Troy meets the Woods brothers, Jonathan (Puppeteer) was friends with them but he didn't really fit in. He voted on to never be friends with anyone again, but when he sees Helen, Zero, and Angel being good friends, he wants to be friends with them too. But he doesn't want to be hurt again. Helen, Zero, and Angel does want Pup to be their friend, they just thought he needs a lot of space. Until then, they all became best friends.
I also headcanon that their friendship is like The Fruity Four (Steve, Eddie, Nancy, and Robin) from Stranger Things