More of Leo.
The guy really has a tragic fate. Yes, he’s an asshole, but regardless of how the story goes, whether Carl dies or not, it’s clear that something changes in Leo. Basically, he grew up knowing that it was easier for his biological dad to just pay money instead of taking part in his life. It is known, that Carl first met him when the boy was 16. In the game, he’s already 28, and I think he got hooked on red ice after meeting his dad. So clearly it didn’t go nice and smooth with their relationship even before the addiction. So it is no wonder he’s so hostile and jealous when he appears in the game. It doesn’t justify him, but at least explains his behavior.