Itachi backstory: he killed almost his whole clan except Obito and Sasuke. Sasuke wants to kill itachi for revenge on his clan. Itachi is a part of the Akatsuki. His partner is the shark-man, kisame. He knows the amaterasu. He knows genjustu, he can use this eyes or is ring to cast a genjustu on you if you dare look at the ring or his mongekyo sharingan eyes. He is calculating, serious, not usually the joking type.