Star Wars Personal Theory V

Continuing my once-a-year visit to the Star Wars movies, I'm also continuing to think through a few "personal theories" I've been forming for a while now. I admit most of them seem pretty much the type that "dwells on the characters" and doesn't get into anything that might be seen as "deeper" analysis, but "everything in moderation" might even apply there too. One of the theories is "when Darth Vader proposed that Luke could be a powerful ally, he was really issuing an open challenge to the Emperor; both of them understood this so well they didn't need to comment on it."
( Ramifications of a 'Rule of Two' )