Mike Miller didn’t deserve to die such a horrible and lonely death. (If that’s what happened, but it probably was. It was.) He was scared of dying such a horrible and lonely death. When he’s told most of the planet’s population died in their own beds amongst their families, he’s relieved, which is so telling about him, right up until he learns just how horrific their deaths were. It’s implied his grandmother’s death was horrific too and he was scared, he turned and ran away from that.
Mike probably guessed what might happen to him, he’s a scientist, was a scientist, he knew the score. He just wanted to see his brother and be a stupid immature kid with him again, see people again, kiss a pretty girl again. He got his wish for about two weeks, not long, it’s more than the other virus survivors got but it’s really not long. Lewis’s boyfriend is dead and Carol’s mother is dead and Gail’s son is long since dead but Mike got two weeks.
y’know Mike probably never worked for anything or sacrificed anything in his life. He didn’t have to, everything came naturally to him. But dying in such a way as to leave as little pain as possible to your loved ones, that’s hard, the hardest thing anyone could ever do. He might not have died in the house, he would’ve known Phil would come back after a week or two and he wouldn’t have wanted his last remaining loved one to have to view his corpse. There were a lot of graveyards to choose from, the whole world was a graveyard in fact. Maybe he remembered the medical centers with their neatly laid out corpses and went to the nearest one. Maybe looked for and found a gun in one of the many abandoned houses and used that, knowing how slow the virus was and preferring something quick.
there was no grave and no special treatment for the golden boy, he’d had more than enough already.
Mike probably never worked for anything or sacrificed anything in his life but he sacrificed everything for Phil. he didn’t give up his life, that was already taken from him, but he did give up his death. What he did for his brother eventually gave him some hope, a fool’s hope sure, but still the most important thing in any world let alone an ended one. Mike died alone and lonely and probably in pain but he almost certainly died at peace.
or I hope so.