After transmigrating as an Uchiha, with no System, no golden finger, and no Sharingan, and facing the Nine-Tails' attack and the terrifying night of the clan's destruction, he can only wait to die.
He originally planned to wait until after the Nine-Tails' attack, then convince his older sister to go into hiding with him. But she was killed on a mission, and he lost both his eyes.
The Uchiha's eyes are a curse. As he experienced pain, Uchiha Xiao awakened the Mangekyo Sharingan.
His left eye, Gluttony, can devour and fuse Kekkei Genkai. His right eye, Imitation, can temporarily copy a target's abilities, including Mangekyo abilities.
He now has the means to take revenge, but knows revenge alone will accomplish nothing. He knows this world has the Rinnegan, and that the dead can be brought back to life.
He chooses the path of darkness, takes Kakashi's Sharingan, and stirs up turmoil in the Shinobi World under Obito's identity. Relying on his own abilities, he will unleash the true Infinite Tsukuyomi, bringing an end to war and conspiracy in the Shinobi World.
