Title: Requiescat in Pace, Bruce Wayne
Author Notes: DC has given some spoilers about Bruce's return (that he will return was, of course, only to be expected). I haven't seen them, but I'm guessing they have nothing to do with this.
He can rest. Human civilization is barely beginning. There's little society, and no crime to speak of. Nothing for him to do. The timestream is too fragile as it is, and Gotham is a mirage in the far future, so to preserve his city he will do, for once in his life, precisely nothing at all.
The Paleolithic sky is clean and beautiful. Bruce rests on a shallow hill, looking at the stars with eyes that feel younger than they have any right to. Perhaps it's the world, or perhaps just himself.
It's a young planet. Ten thousand years, give or take, before Earth has the technology and organization to resist invasions from space, or to keep immortal madmen like Ra's al Ghul and Vandal Savage in check. Only sheer luck had stood between humanity and them.
Bruce sighs, entirely unsurprised by what some of his least empirically-minded colleagues-to-be would call 'fate'. Standing up, he begins calculations to orient himself using the far past's stars. It's probably around a thousand miles to the nearest Lazarus Pit.
He has a long journey ahead.