Re: Batman: 1 parent instead of 2
In Alan Brennert's classic story "To Kill a Legend," the Phantom Stranger takes Batman to a parallel Earth that's 20 years behind his own and gives him a chance to prevent the murder of that world's Thomas and Martha Wayne. In the end, he succeeds in saving the Waynes, but young Bruce is inspired by the vision of the bat-winged hero who saved his parents to pursue a heroic path of his own. "And when he does, it will not be a decision born of grief, or guilt, or vengeance... but of awe... and mystery... and gratitude." So even without the tragedy, he still becomes Batman, but a more upbeat Batman.
So, in other words, as Ethros
suggested, he had time to prepare...
"That which can be asserted without evidence can be dismissed without evidence." -- Christopher Hitchens