The French Mistake by @Vamillepudding.ao3
The universe Bruce wakes up in has superheroes, aliens and, somewhat more strangely, it also has four children living in Wayne Manor. Bruce Wayne is almost forty. He's been an innovator, a philanthropist and GQ's Most Wanted twelve years counting. He doesn't remember being a dad. But now that he is, he's going to be the best dad one could possibly be. Or: Batman is a dick. AU-Bruce saves the day. This is sweet and funny right up until it punches you in the gut with heartbreak.