I've read the next chapters. Leon becomes pathetic; it's horrible to see.
SPOILER:
He's raped by the red-haired guy in werewolf form and vomits blood as he's torn apart, then saved at the last minute by the gray-haired guy. I imagine he'll make it, but frankly, I'd rather he die than continue witnessing all this violence.
Season 3 concludes with episode 100, in which Leon completely surrenders himself to the other four characters. Honestly, I don’t think there will be any revenge, nor will Cliff return to the main storyline. I believe it’s essentially a "mind break" story.