Louis in Season 4
Louis literally loses his ever loving mind in season 4 after he gets fired and then finds out about Mike.
I think most of why he’s so mad is because he’s always feeling inadequate and never feels fully accepted by Harvey, Jessica etc. He’s been desperate for their approval for years and Mike instantly was taken under Harvey’s wing. and then to find out he didn’t even go to law school, and everyone knew except him, and everyone protected Mike for years just makes Louis spiral. He’s insanely jealous of Mike, and that’s what makes him act like such an asshole.