I am writing an 'apocalypse' story, after a fashion. It's a black comedy. I'll try to be brief. (HA.)
It's actually apocalypse 2.0 because in the setting people weren't completely wiped out in the first go. Just about wiped out, but not totally, and after the chaos they re-adapted.
So this is a few millennia in the after the fact, which was itself a few millennia in the future. 2012 can suck my metaphorical balls. I introduce a few new key ecological factors due to interstellar contamination from apocalypse 1.0 and blah de blah de blah.
Essentially you have this dude right, from back before apocalypse 1.0. His body doesn't really deteriorate and can rebuild (within reason, if he's atomized... then it's not looking so good for him) due to accidental quantum computer-esque molecular blah de blah de blah. But he's seen a lot and has been alive for a rather long time and this hasn't done nice things to his mental health.
So one day he decides to start fucking with the rather fragile re-built societies. Because, well, because he can. The story revolves around that, a horrifically powerful hive-mind that he accidentally creates, and other things that spiral horribly out of his control. He essentially enlists the unwitting help of a de-aged-to-about-17 woman and her genetically engineered, forced-marriage Brigadier General husband, and to an extent, the woman's also-genetically-tinkered-with-but-still-actually-human former husband (from back when she was still 30, not 17...and could remember what the hell was going on) to dismantle said hive-mind, thus letting him continue to fuck with the remnants of humanity. Things go down-hill from there.
It should be fun.