Deku goes back in time and becomes Rei Todoroki

Then the world snaps back, in the form of a kettle whistling, high and piercing.

"Mom?" a little voice says, and Izuku feels his heart pound as he turns and looks down at a small child with half-red and half-white hair, peering up at him around the edge of a door with confusion and fear on his face.

Or~

The current number one hero and symbol of peace, Izuku Midoriya, is sent back in time and into the body of Rei Todoroki in order to fulfil his wish to protect his best friend, Shoto, from the things that happened to him as a child.

Warning: This story mentions abuse (Obviously, it's about the Todoroki's), if that makes you uncomfortable, please do not read this fic. Other than that, Enjoy!