So, in the comics, at one point Hydra gets involved with making zombies. That happened, it's a thing, I don't remember why and I don't care. Anyway, since everyone else's best friend already came back from the dead in the MCU, Hydra doesn't have a lot of corpses they can get their trashy hands on to traumatize the shit out of Cap's team. There is, however, one unfortunate fucker buried in Arlington that no one's been paying attention to. . .

That's right. Hydra digs up Riley's mutilated body and gets him shambling through a mix of dark magic, Tesseract tech, and weird science. Their experiment has left his bodily fluids (blood, saliva, and semen) corrupted, priming him as the Subject Zero of a zombie outbreak, and for whatever reason, he's got a surprising amount of cognitive function, so while he is a rotting undead mess, he's also still basically the same guy beneath the sometimes ravenous hunger for brains and human flesh.

Sam is, understandably, horribly upset when he finds out, and embarks on a mission to rescue his wingman. And well, this prompt wouldn't be garbage enough for this meme without me requesting that they fuck after being reunited.

My little necro-creeper heart will overflow for any of the following:
+ safe sex practices to keep Sam from turning into a zombie too
+ a brutal, consensual face-fuck because Riley doesn't actually need to breathe
+ Riley bottoming because without a heart beat he can't get enough blood to his dick to hold an erection
+ Sam fucking one of Riley's open wounds BECAUSE WHY NOT