actually i saw the series from middle in the tv....
你 should try to go back and watch all of 火影忍者 if 你 can. It will really help 你 know and understand all of the character's feeling and actions. I know it is a lot of episodes but it will be worth it later on :)
Because Itachi killed everyone in the uchiha clan (including their parents) leaving only Sasuke alive. That's why Sasuke hates him and want to take revenge on him 由 killing him.
He killed Sasukes Parents and everyone in his village. He was so cruel. Sasuke at that time was only a kid so he could not save them. And it is his aim to defeat Itachi I agree with everyone else. Try watching 火影忍者 from the Start. :)
