Be very, very careful trying to pull tricks on NPCs with immense wads of power and the cunning to rise to that position through their own sweat and toil. It's like trying to blackmail Batman. It's just never going to end prettily.
Darth Vader: What... What have you done to me?
Palpatine: I need a strong figurehead to control the military; you shall have the power you crave. Do not deny it; I have sensed it building in you.
Palpatine: The midi-chlorians have supported your shattered body; they will help you grow strong again.
Palpatine: But the military chain of command is very... traditional.
Palpatine: You are now effectively a retired Jedi; you should adopt the "Darth" honorific.
Darth Vader: I shall be known as... Darth Vader.
Palpatine: I regret to say, your life support systems contain... measures to ensure your loyalty.
Darth Vader: What do you mean?
Palpatine: You are too dangerous, too... reckless; you must learn control. Until you do, I shall be your master.
Palpatine: Now, get me some tea.
Darth Vader: Noooooo!!!