When fredo arrives in cuba with the 2 million , and meets up with michael in his hotel room fredo asks is there anybody around he knows , Michael names roff and johnny ola then asks fredo if he knows them which fredo denighs . forwarding on to the new years eve party , when michael introdues johnny ola to fredo he says "oh you dont know my brother freddie do you " Was this juat an inocent introduction or did michael smell a rat , as of course if fredo did not know ola , why should ola know fredo .

This is one (among many) of the most hotly debated subjects on the Board. I don't think he did suspect him. He was just answering Fredo's question and later at the nightclub he is just introducing them.

Some people here think Michael suspected Fredo because of the searching looks he gives Fredo at two points: when Fredo asks if there's anyone in Havana that he knows; and at the nightclub when he says to Ola, "I don't think you've met my brother." Could be. But then we have to take into account that Michael asked Fredo, "Can I trust you with something?" and then told him that Roth would never see the New Year. And, Michael's absolutely devastated when Fredo makes his fatal gaffe at the Superman show.

I believe that Michael was telling the truth when he told Tom, after the shooting: "Right now, you're the only one I can completely trust [emphasis added]...Fredo? He's got a good heart, but he's weak and stupid, and this is life and death." I think he meant that he didn't suspect Fredo of deliberately betraying him ("good heart") but that Fredo might have inadvertenly contributed to the shooting through his own stupidity. So, when Fredo made his fatal gaffe, Michael was devastated to learn that Fredo was consciously conspiring with Roth and Ola.

Do you believe that Fredo told Roth about this plan?

Good question!
Logically, Fredo would tell Roth, since he'd seemingly cast his lot with him. But, logically, if Michael couldn't completely trust Fredo, why would he tell Fredo about his plan to whack Roth? And if Fredo had told Roth, why didn't Roth accelerate his plan to whack Michael?
One thing seems clear: By the time of Michael's last meeting with Roth ("Who had Pentangeli killed?"), both of them seemed to know each other's plans. What makes the scenario convincing is how both of them were hanging tough at that point: Roth holding out for the $2 million, Michael holding out for finding out who the traitor was in his family.

Michael loses nothing by telling Fredo of Roth's plan to assassinate him. By that point both Roth and Michael knew each was a danger to the other. Michael also knew that in all likelihood Roth would not be joining him and all the big shots for Fredo's "night on the town." Moreover, it does not appear Fredo ever had the chance to tell Roth.

I am in the camp that Michael had Fredo on his suspect list pretty early on. The loaded question about Johnny Ola gives this away, and Fredo's reaction to Michael's invitation to go spend time together is to confess that "I was mad at you" and
his very anguished statement about the two of them not having spent time like this before. To me this i a dead giveaway that Fredo is the traitor, and it gives Michael the perfect chance to bring his enemies in closer by telling him about the asassination plot.

But Michael increases his own danger by telling him that he plans to kill Roth.

Now wait a minute. What if Fredo tells Roth that Michael knows? Then, any counterstroke Michael has planned goes out the window.

Also, I don't find anything in Fredo's "spent time" statement especially revealing to Michael. Michael knew that had kept Fredo at arms length for years, so it would be natural for Fredo to lament it.

Roth did take counter measures to avoid assassination. He checked into the Hospital and had a group of Batistas guards tome to protect him (in a nick of time).

Also you have to listen to the tone of Fredo's voice when he tells Michael "I was mad at you." It definitely implies he regrets SOMETHING.

The something it reveals is typical of any siblings who regret not spending more time together. But how do you read anymore than that into it? Fredo's statement about being left on the doorstep indicates his feeling of inferiority which Mike has already recognized. But it would be quite a leap for Mike to detect more than that.

No it is more than that. What you describe is more like what went on between Connie and Michael. She also was mad at him and she also was estraged from him, but when they hashed it out, there was real compassion, and she became his caretaker. With Fredo the statements that he was mad, and the rhetorical question , Why didn't we spend time like this before is a thinly veiled admission of his treachery.

Followed quickly by the Michael death stare at Fredo. It was almost like Michael was thinking, you are going to confess and cofirm in my mind that it WAS you!?!?!

Yes, he regrets not spending time in the past as they were spending time then.

And what stare are you referring to? A death stare? I don't see that at all. Of course, if Michael was thinking that, why in the world would he reveal his knowledge of Roth efforts to kill him and his plan to kill Roth? Now that does not make any sense!

Watch that scene. Its there. (Mikey I was mad at you) <<-- right at about the word "mad"

He revealed because he was torn and unsure. It was still his brother and he did love him.