DemonoidKing
Okay hear me out, alright? I was just reading another fanfic while thinking of this one (hoping for more chaps btw) when I realized something. The MC has reactive evolution, and since it could turn him all-powerful, what's the thing most ageless beings will die to in the end? The end of the world. Soooo, if this dude goes into a room where the temperature and radioactivity is slowly raised while the amount of oxygen in the air is lowered, he could eventually live in the center of the sun with no problem. He'd also need to fast tho so he doesn't need food or water.