Ch 1. Merging

All For One, the worst Villain in the history of the entire world. He had killed countless, and destroyed most of Japan during the dark ages of Quirks. Imagine his surprise when he wakes up in the body of teen, not just any teen but the Izuku Midoriya. The worst part was he wasn't just possessing the boy, he had merged. Will his newly found guilty eat him alive till there is nothing left, or will his brother who was meant to be gone forever save him?