Despite what many would believe, the universe does not care about what direction time flows, only that it does. The only ironclad rule was that the world line must be respected. Midoriya Izuku thought that his quirk was a party trick at most, and soon fell out of his childhood notion of being a hero. But when he finds that his power is so much more than he'd thought... Perhaps orderly dreams do not always have to decay into disorder.
...Or, Izuku has a huge mindfuck for a quirk.