I agree with you TB that there could not have been an active plot against Michael until they knew he was going to take over the family business. Keep in mind, however that Michael returned from Sicily "a year, maybe more" before he even proposed to Kay. By the time Michael went to Vegas to tell Moe he was buying him out, Sonny had been dead a long time, everyone knew the Godfather was sick,and thought that the Corleones were being running out of New York by the other families and that they didn't have "that kind of muscle no more." As we have discussed elsewhere on the boards, they also surmised that Michael was the new head of the family, and they also underesitmated him. It would make sense therefore that Moe and Roth (through Moe) would already be working on Fredo to get him to further splinter the family. They would be telling him that he was passed over, that Michael was weak, and that the family was falling apart. When Moe slapped Fredo around, it obviously made Fredo feel what they were saying to him was true. As for Fredo being "happy as a clam" in Vegas, I respectfully disagree. I think he was as happy as that clam which took a stray bullet at Umberto's. I thought he was nervous and edgy. He snaps at Michael when he says Moe said to call "after the party started." He is making excuses to the hookers and the band that Mike dismissed "I don't know he's tired." When Micheal is showing Johnny the contracts Fredo says "Moe never said anything to me about selling... he loves the casino business." And when Michael makes the comment about Moe slapping him around he is overly protective of Moe, saying "Sure he flies off the handle but me and Moe are good friends..." as he is giving Moe a back massage and hoping Moe will say something other than he had to straighten him out. Then of course he takes sides against Michael on the buy out deal. I think Fredo was already having misgivings about Michael's strength and his judgment, and I think he was perfectly set up to betray him later on. For sure, Fredo realized how powerful Michael was when he killed everyone at the end of GF I, but it also solidified him as the one who got passed over, and was probably seen as a pawn in Hyman Roth's long term schene to avenge the death of Moe Green.