Well, if Reader is being very aggressive, such as biting, scratching, clawing at others, or lashing out, or trying to run for the 72nd time, the platonic yans might chain them up in a special room, so they can't keep doing it. It will also make it easier to sedate/drug Reader, since they would have limited movement and not be able to leave. The cuffs are padded, likely colorful, and the room is likely padded and in a pastel, light, or neutral shade, no white or black walls or too bright lights or too dark room, as that might traumatize Reader more than they already have been. So, the cuffs could be on Reader's wrists, being chained and bolted to the wall or floor, padded and/or fluffy and likely have stickers on them.. Or they could have cuffs on their ankles, bolted to the floor and giving them a limited amount of pacing/walking space, also padded and likely smooth, maybe they have a mechanism inside, like a small hidden needle, that can inject Reader if they have a panic attack or try to hurt themself or are generally being an angry wet cat of a teen. Reader could even have a cuff around their neck, with a chain long enough that they won't choke or be able to strangle themself, extra padded, also has a hidden needle to sedate them, and likely used if they are trying to bite people (and Reader has a strong bite force).