What was Stalin's beef with Trotsky? That he was of Jewish descent?
There was one school of thought about Germany's attack on Russia: "Let the monsters (i.e., Stalin and Hitler) devour each other."
The decision was made that Hitler was completely insane, but that you could work with "Uncle Joe."
Stalin just wanted power, and the Bolsheviks were just his vehicle.
He was more of a fan of Ivan the Terrible, than Karl Marx.