I have no deco, I took it all out. But it seems as if the little asshole starts the fights and the other three just put him in check by chasing them away and in the meantime nipping him, you'll be able to see better with a pic I think he's ok though.
it seem like he is just stressed out, and is trying to fit in and not get killed. P's tend to change colors depending on the mood they are in. I would keep a close eye on him and seperate him if needed.