Au where the party finds out Eddie is alive in the upside down and they all reconvene at the Hopper-Byers household to figure out what happened to Eddie after Jonathan went to take out the trash one night and found an undead feral Eddie rooting around the bins

Once all together, El is trying to peer into his mind and something triggers in Eddie that makes him tackle Steve to try and take a bite and then it become a vampire Eddie who won't let go of Steve, the feral part of him baring fangs and constantly trying to pull Steve into his lap to scent his neck

(Extra bonus he manages to lick Steve's face before Hopper and the others finally manage to pry Steve away from him before he went to town with the blood drinking)