If not ex-military, I'm maybe leaning more into the idea that he has a past life in organized crime; really favoring a relatively violent/dangerous history to have brought him to where he is now. Or maybe even some kind of occult involvement.
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Ohhh dude I just thought of an amazing one for the paramedic. It could be like a soul siphon with the ability to heal others by siphoning their pain and suffering, but at the cost of taking on their emotional wounds and mental scars. It's like a double edged sword: the more they use it, the more they lose their sense of identity xD Idk. I'm just babbling.