My god, I have fully submitted myself to being a piece of trash. Here we go:

I don't have any specific demands, just trashy and disgusting human experimentation done on Bucky while he is being raped, especially taking advantage of his ability to heal. Some ideas:
- Vivisection without anesthesia, to "study" his body, while being fucked with toys
- Removing sections of his muscles and bones that make him more fuckable (i.e. removing parts of his jaw so he can deep throat better) and then putting them back later
- Pumping his body full of diseases/drugs/poisons to see how he reacts, and then using his compliant body
- Starvation
- Long-term sensory deprivation

Basically give me the most disgusting shit possible. Anything goes.