I totally get that!I kinda have a blood kink as well. Also into some very light guro. For me though, besides the aesthetic of it, it just makes me instinctively sympathetic/protective. Probably also something to do with vulnerability.
Although, for me the whole sympathetic/protective part usually kicks in during aftercare, or just generally when sex isn't involved - if I see my partner with a nosebleed, I'm obviously going to prioritise helping them rather than having sexy times.
I definitely think the aesthetic plays a huge part as well, probably more so than everything else.