Fredo? Yes.
He shows up drunk at Connie’s wedding in the beginning, and when Don Corleone is shot at the fruit market Fredo fumbles his gun, allowing Sollozo’s thugs to get away, and he sits down in the gutter and weeps.
And this I believe is from the first
Godfather
Casino owner Moe Green takes Fredo on
and slaps him around because Fredo was
“banging cocktail waitresses two at a time”. Fredo to Mike: “You don’t talk to someone like Moe Green that way!”
Mike: “You’re my older brother, and I love you.But don’t ever takes sides against the family again.Ever.”
Michael later has Fredo shot to death.
(Pt 2 I believe)—but waits till their mother is dead, first.