Soul Turned Red

Three siblings, two alive, one dead... or is he? Apocalypses have been talked about for decades, but no one expected one to happen, especially one where a monster's bite can turn you into one of them. Most of civilization has died in the four months of this, whether by choice or turn is constantly changing, however it all leads to the same end. There are a few survivors left but these three brothers hadn't meant any others personally until they were surrounded by the monsters and one of their own got bit. He stayed behind but the other two were discovered by the group. What will happen when the monster their brother was turned into starts trying to find them? And what will the group that took the other two in do when they realize he isn't quite like the others? (Sorry for the bad description.)