The animator made Second as a stick that he could torture all he liked before killing. But Chosen just so happened to be watching, and couldn't stand seeing the innocent stick get beaten up for absolutely nothing, so he after accepting death intervenes and tries to protect the Second
The animator then gets an idea, and decides to keep Second around to basically blackmail Chosen into not fighting back. Second and Chosen figure this out by themselves
Chosen doesn't care about why Second is here, he's just happy he is here (and by that I mean alive). Second sees himself as dead weight no matter what Chosen tells him