The worst part of Godfather II was Michael’s devoted henchman. His character just seems to pop up out of nowhere without any explanation.
I had never thought about it but you are right.
Now that I think about it, Michael had two henchmen. The really rough looking one who wore a hat and was killed by the Cuban officer and the smoother one you saw most often in Nevada.
BTW, I think “The Godfather” is quoted more than just about any movie ever made.
His character gets a number of pages in the book, as being a cop who gets busted out of the force for killing a guy who had come at him with a knife, and who is bitter at the perceived raw deal until Don Corleone hires him into the family. There's a lot from the book that they had to cut from Godfather I. A lot of it made it into Godfather II, but there still was a lot cut.
If you read the novel, it’s better explained how Albert Neri came to become Michael’s henchmen; he was brought in as a make-shift Luca Brasi; I guess they either edited out any backstory about this, or they chose not to include it in the script for fear of complicating an already multi-POV/multi-stranded storyline, and confusing the audience.