In the scene where Luke surrenders to Vader (in Return of the Jedi) what is Vader feeling? Is he genuinely regretful that he has to hand Luke over to the Emperor?
In short, what exactly are the emotions Vader is going through at this stage?
He's feeling a pull to the light side of the Force. This is provoking fear.
But Luke isn’t going to be distracted.
“Come with me,” he says.
Now Vader truly understands why he has feared his son so much. Not because of his mastery of the Force or skill with a lightsaber. But because Luke can make him question the dark truths that have long ruled him.
He's certainly feeling a whole bunch of pain and remorse (which he uses his dark side powers to quell)
“Search your feelings, Father. You can’t do this. I feel the conflict within you. Let go of your hate.”
Luke’s attack has at last reached into the great, dark, troubled mind of Anakin Skywalker. And to Vader it is far more painful than the lightsaber slash Luke scored in Cloud City.
The junior novelisation implies a great deal of regret
“Search your feelings, father,” Luke interrupted. “You can’t do this. I feel the conflict within you. Let go of your hate.”
If only I could, Vader thought. If only I could.
He said, “It is too late for me, son.”
He's pretty ambivalent about sending Luke to the Emperor.
Vader stepped to the railing and tried to collect his thoughts. I must obey my Master. I must deliver Luke to him. But if Luke can kill the Emperor, perhaps … perhaps then I will be free.
There's also a certain amount of pride in his offspring having become both a skilled Jedi and a young man.
“It is the name of your true self.” Luke’s gaze bore steadily down on the cloaked figure. “You have only forgotten. I know there is good in you. The Emperor hasn’t driven it fully away.” He molded with his voice, tried to form the potential reality with the strength of his belief. “That’s why you could not destroy me. That’s why you won’t take me to your Emperor now.”
Vader seemed almost to smile through his mask at his son’s use of Jedi voice-manipulation. He looked down at the lightsaber the captain had given him—Luke’s lightsaber. So the boy was truly a Jedi now. A man grown. He held the lightsaber up. “You have constructed another.”
Being referred to as "Anakin" provokes anger.
Luke addresses Vader as Anakin Skywalker, and urges him to let go of his hate. But Vader reacts angrily to that name. He says Luke must obey the Emperor, and takes his son to face him.