beta
What if big guy has sorta mind power that if his community don't behave, they get hallucinations nightmares or such that he haunts them; and because it didn't physically happen, the people doubt it's real and continue their happy settlement, but the fear from their 'punishments' lingers. Big guy doing same to uke but lewdly so as if somehow big guy knows people's unspoken desires or intentions. Nifty ability to keep everyone in check, as he's the leader after all.
Makes more sense if it was chilly then they have sex to keep warm. But if it's already hot, sticky musky heatstroke then.