• Fredo's “there was something in it for me -- on my own"

I doubt the astute, meticulous Roth would master plan such a do or die, critical operation of murdering a Don, in his own home, in his bedroom, without specifics [on vague / implied] without making it clear to Fredo that the reward is Donship or Roth would have instructed Ola to make sure Fredo listened good and inferred it [Ref: Turnbull] Hooked!

They need to ensure, imperative Fredo opened the drapes thus identifying Michael and Kay's bedroom, which is obviously of vital importance to the Tahoe shooting without which there can be no assassination and only the Donship carrot would get the job done

Besides even Fredo would have known there was no way he could operate outside the Corleone business, something on his own
Fredo knew the only way “Fredo wouldn't be stuck running Mickey Mouse nightclubs” is if Michael was dead

Originally Posted by Evita
Extract: He [Fredo] might have been mostly honest with Michael about how the meeting with Ola went but everything before and since was devious, dishonest, deceitful and he was quite the deep thinker, coming up with all those lies, lie after lie, he was feeding Michael

Quick and Clever too including after Ola's phone call
Quote
Deanna: Who was that?
Fredo: Ahh -- wrong number --