Because of the violence of war Itachi experienced during his early childhood, he longed for peace and wished to achieve it at any cost. This was the reason why he became a double agent when his clan planned a coup d'état against Konohagakure. He was given orders to assassinate all of the Uchiha, but could not bring himself to kill his younger brother, Sasuke. He made himself out as a villain and joined the criminal organization, Akatsuki, continuing his work as an agent of Konoha.
Beautiful cosplay! I’ve always liked this character despite being the villain in Naruto. Thanks to Trida for sending this!
EDIT: Thanks to anon for commenting the cosplayer is Jesuke!