eyy so this should b a fast answer hopefully
basically u want stuff that can be done in one night, and isn’t too serious?
so for actual damage
They could remove one or two of his finger/toe nails. Not all of them!! that’s serious!! but one of two would b Very Painful but Not A Big Deal. that being said, they’d have to be some pretty awful counsellors to let that pass.
they could also repeatedly knock the wind out of him by hitting him in the solar plexus. This is Terrifying, but not a big long term deal. Standing on his gut would be awful as well, but not stomping! just putting weight on his belly. contorting his limbs into awkward positions for long periods of time would also be scary and terribly, especially if they teased him with threatening to break his limb, but never going through with it
back to stepping on him- it could be really awful if they tried to make him wet his pants on a psychological level, even if he doesnt actually wet himself
also just, taunting him. Making him feel weak over crying, over being upset, over all the abuse. ‘it’s not that bad’ yes it is chad you torturous fuck
i think that should cover a night just fine!! Good luck!!