Naruto: Byakugan Wolf Itachi? Call Me Uchiha Uranium

That year, an unparalleled genius appeared among the Uchiha. Born with the natural gift of dual pupils, Uchiha You was hailed alongside Minato Namikaze as one of Konoha's twin stars, and became a powerful contender for the title of Hokage. He wielded the power of uranium-235 and the power of biological hazards.

During the Third Shinobi World War, Uchiha You single-handedly held off Iwagakure, only for Shimura Danzō to conspire with Iwagakure from within and seal him away.

By the time Uchiha You broke the seal, the Uchiha Massacre had already begun.

Uchiha You: "My left eye is mutually assured destruction, and so is my right. Pick one."

The Byakugan-bearing traitor Itachi: "What do you mean your left eye has high radiation and your right eye is highly biohazardous?"

Shimura Danzō: "Wait, what do you mean my genetic chain broke and reformed? Why am I deformed and craving human flesh?"

Orochimaru: "What do you mean you can bring the dead back to life and make them immortal, but they'll lose their minds?"

Madara Uchiha: "What do you mean your mutually assured destruction has different levels? Ten kilotons? A hundred kilotons? A megaton? Ten megatons?"

The Ōtsutsuki Clan: "What do you mean we're the best corpse servants?"

Years later, posterity would call Uchiha You's Sharingan the World-Ending Sharingan!