Titled for the song of the same name by A Great Big World and Christina Aguiliera, though the cover by Pentatonix is largely what drove me.
Title: Say Something
Universe: Justice League/Young Justice Amalgam
Characters: Batman/Bruce Wayne, Wally West/The Flash, Alfred Pennyworth
Description: Bruce gets older, grayer, and slower while Wally remains as bright as ever.
( Reality is not so black and white. )