pyro has pretty bad medical trauma from growing up in and out of various different hospitals and psyche wards. Their parents were killed in a house fire when they were young and they were the only survivor, but with severe burns. After multiple surgeries they were stable but completely different in appearance. They refused to look in mirrors at first but it quickly got so bad that they would cover themself entirely and when they needed checkups they would have violent outbursts and often had to be restrained with force or sedated.

Eventually they were transferred to a mental hospital for hallucinations and these outbursts. They were transferred multiple times for trying to hurt patients and staff along with purposely starting fires, which made many staff that worked with them begin to theorize that they had started the initial fire that killed their parents.

So when they started work as a mercenary and met medic they hated him immediately. No doctor had ever wanted to really help them, especially not this dude. He was unlicensed and had an obsession with invasive, uninformed surgeries that they wanted no part in. They allowed checkups, and eventually were forced to agree to surgery for the uber hearts since they were being implemented as an important part of battle.

And of course, he was weird about it, because he’s medic. Very fascinated by their scars and medical history and everything. There’s nothing they hate more than the morbid medical interest in their fucked up body that every doctor seems to have but his was a lot different. His attention was more akin to reverence and admiration in a way that made them both feel terrible disgust and great comfort.

After that, though, because he finally got a proper physical evaluation on them medic realized there were a lot of medical issues that pyro had been masking and he starts requiring more frequent treatment and checkups, which kinda starts affecting their mental health, but because medics affection is violent and gruesome in nature he goes about things very differently and is oddly comforting and caring about it

and it kinda turns into a messy situation where they know they’re his guinea pig just like everyone else but they’re his favorite guinea pig and they like that a lot, even if they won’t ever admit it.

When homoerotic situationship dissects you but it’s ok because he cuddles you and kisses you after and you like being hurt anyways.