What I find very odd about the book is that there are a ton of pages on Johnny Fontane, Lucy Mancini, and Jules Segal, and there is barely anything about any of those people. Segal is indirectly mentioned when Fredo says to Mike when he arrives in Vegas "Wow, that doctor really fixed you up good!" Lucy Mancini is totally nameless in the movie and appears only at the wedding and in her apartment. Johnny is the only one that gets more than 10 seconds on the screen. But even then, none of his troubles with his wife and ex-wife are covered. THe don only asks if he spends time with his family and according to the novel, he really doesn't.

"And that by chance if an honest man such as yourself should make enemies, then they would become my enemies. And then they would fear you."