i would have to say fredo. i thinki read somebody earlier saying it was one of the most emotional betrayals. and no pun intented but it trule "broke my heart." its just sad to see how deep mike had gotten into the business and how he lost it all. another thing the scene between micheal and kay where kay reveals to micheal that she had an abortion. it was such an emotional scene. one of my favoites. its still boggles my mind that pacino didnt win an oscar for any of the godfather films. i mean great performance in scent of a woman but i mean he was just so brillian in the trilogy.