As we saw here, Vader made this proposal to Luke:

Luke, you can destroy the Emperor. He has foreseen this. It is your destiny! Join me, and together, we can rule the galaxy as father and son! Come with me. It is the only way.

But, before the duel on the second Death Star, Luke threatened the Emperor's life and Vader prevented him from doing so. Why did Vader do this? And if Vader's goal was to destroy his master, he had him at his mercy at this point:

The Emperor at the mercy of Vader

Why didn't he just twist his wrist to kill the Emperor himself?

  • I always assumed Luke's strike was actually aimed at Vader not the Emperor. Look at the angle of Luke's blade in the Screenshot, funny angle to strike at someone if you wanted to kill them..
    – Jared
    Commented Jul 20, 2012 at 0:19
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    @Jared Vader's lightsaber intercepted and deflected Luke's strike, but it was aimed at the Emperor. The Emperor is goading him into doing precisely this! "Grab your jedi weapon and strike me down"
    – Andres F.
    Commented Jul 20, 2012 at 3:01
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    @jared also, if you watch Luke's fighting style, he pretty much just swings like a baseball player instead of as a true swordsman, like vader.
    – DForck42
    Commented Jul 20, 2012 at 15:36
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    @Jared It's a giant stick of glow that vaporizes anything it touches. The angle isn't quite so important as with our metal swords.
    – jpmc26
    Commented May 23, 2015 at 2:26
  • It is not certain that not parrying Luke's strike would end up with the Emperor's death - the Emperor might have been using some sort of a Force field that would have stopped Luke's blow anyway right before his lightsaber touched him. Commented Nov 16, 2017 at 15:27

9 Answers 9


In the novels, Vader is working to get Luke to fall, as is Palpatine, but Vader wants Luke to swear loyalty to him, and not Palpatine.

The first goal is to get Luke to actually commit himself to the Dark Side; righteous anger is too easily quenched by reason. Luke could have killed Palpatine there and then, and then gone right back to the Light leaving Vader alone, or even turned on Vader after killing Palpatine. Palpatine said it himself: "he has grown strong; only together can we turn him towards the Dark Side of the Force". So, Vader had to defend Palpatine because the first goal had not yet been met; Luke had to see that hate was power, feel it coursing through his veins, in order to give himself to the Dark Side. He wasn't there yet when he first struck at Palpatine.

However, by defending the Emperor and thus forcing Luke to fight him, Vader took the focus off Palpatine. He was too good at getting Luke riled up, especially when he discovered Luke had a twin sister and used that to provoke him. Luke forgot all about the Emperor and focused all his hate on Vader, and it wasn't until the Emperor's laughter jarred Luke out of his battle haze that he realized just how close he was to falling and stepped back.

Vader, at that point, had lost completely. Luke wouldn't turn, and if he had it would have been at Vader's cost. Vader really had no choice but to crawl back to his master's side. Except... if Palpatine won, the Skywalkers would die; Palpatine had already shown that he considered Vader to be just another pawn, to be sacrificed for his own ends. Luke would die on the Death Star, and Palpatine wouldn't stop until Leia was dead too (and she was on Endor; in the novels, if the shield ever came down, Jerjerrod was under orders to destroy Endor). Vader had loved Padme even after falling, and seeing their children suffer, watching one being tortured to death and knowing the other was right behind, was just too much. He found another option, the one he never would have considered under any other circumstances; destroy Palpatine himself, turn on his master, end the Sith, to save not only his son but his daughter as well.

  • Is that in the novelization of Episode 6, or other EU ones?
    – Xantec
    Commented Jul 19, 2012 at 16:47
  • Episodes 5 and 6.
    – KeithS
    Commented Jul 19, 2012 at 17:14
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    +1 but you forget something else important. The Emperor was very powerful in the dark side of force. Do not confuse apparently defenseless with actually defenseless. Failure to kill on the first strike would be fatal.
    – Chad
    Commented Jul 19, 2012 at 19:48

I always thought Vader acted to prevent Luke from completely turning to the Dark Side. Luke was the only one who believe that Vader had goodness still in him.

Vader was never really cut out for the Dark Side. In episode three, iffy acting aside, you can see Anakin is tormented by the decision to side with Mace Windu or Palpatine. He finally chooses Palpatine not out of a desire to be bad or to control others, but because he believed it to be the only way to save someone he loved. A selfish act for sure, all the Jedi were a little arrogant and prideful, but this one act was hardly worthy of the grand schemes that Palpatine had been cooking for decades.

Once Luke made it plain that he believed that Vader could be redeemed, Vader had a hard time letting that ray of hope go. So while Vader wasn't yet ready to completely rebel against the Emperor, he was unwilling to let this one person who believed in him, who was his own son no less, commit the same act of self betrayal that he had so long ago.

My 2¢ anyway.

  • 4
    Excellent answer. And I'd give it an extra +1 if I could for the "iffy acting aside" comment!
    – eidylon
    Commented Jul 19, 2012 at 16:43
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    There is little shortage of documentation of people thinking Hayden Christensen incapable of acting... and citing Eps 2 and 3 as reason. "iffy" is a gross understatement.
    – aramis
    Commented Jul 22, 2012 at 2:29
  • The acting is not iffy. Anakin is what, 15, 17? something like that? Super strong, fights all day, and only knows one woman. We say the acting is bad because we remember being that age but we picture talking like ourselves. Teenagers are ridiculous, and the boys don't talk. Anakin is 10 years away from having the polished, disciplined game. He's still young enough to do what he's told, but old enough to be sullen about it. He's very emotional, but whiny, just like we all were. I thought it was perfectly done. He should be irritating! The words came out weird because that
    – chiggsy
    Commented Jan 7, 2016 at 6:06
  • He's very emotional, but he's gotta keep it locked down. He's whiny with Padme because he met her as a kid, and he spills his guts. She loves him, because she apparently is a person of dubious character, he was a little kid when she met him, and sure enough, things go to hell. The best case scenario for Ani is that he's a dad at 17. No more spaceships and sword fighting. It takes time to look cool while you are in tortured mind, and he's just a child soldier. He played it quite well.
    – chiggsy
    Commented Jan 7, 2016 at 6:41

To answer the question directly, remember also the Rule of Two. From Wookieepedia:

This transfer of power would only take place when the Apprentice takes their Master's life

The Apprentice has to take the Master's life. If Luke struck the Emperor and killed him, it would make Luke the master. Vader had to intercept if he desired the the Master role.

  • 1
    Then, why he didn't kill him just after he intercepted Luke's strike? The emperor was defenceless at this moment.
    – DavRob60
    Commented Jul 19, 2012 at 23:35
  • 4
    I have not read any official canon specifically addresses this, so I am just speculating at this point. One possibility: Palpatine was actually preventing Vader from killing him. Whether through the force, or simply by being aware of the situation (preventing Vader from taking overt action). In this particular scene, Palpatine is very focussed and alert to his surroundings. However, when Palpatine is shocking Luke, he is quite consumed in the act, and would perhaps be distracted and vulnerable. Perhaps Vader was just waiting for the right moment to strike. He would not get a second chance. Commented Jul 20, 2012 at 3:35

At this point in the story, Vader was still "loyal" to the Emperor. This is evident by the events that took place in A New Hope, Empire Strikes Back, and the first half of Return of the Jedi. It wasn't until Palpatine began frying his son that Vader turned his back on the dark side and redeemed himself.

As far as the proposal, it's hard telling whether it was genuine or if it was just a tool to draw Luke to the dark side. Their are definitely arguments for both.

  • But, the first task of a Sith apprentice isn't to destroy his master?
    – DavRob60
    Commented Jul 19, 2012 at 15:34
  • But that generally happens at a point when the student believes they have become sufficiently powerful enough to defeat their master. Vader was asking Luke to join him and help him defeat Palpatine. Luke, who has had minimal force traning. Clearly Vader didn't believe he was strong enough to take on Palpatine alone.
    – Ryan
    Commented Jul 19, 2012 at 15:39
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    Yes, but Luke was already attacking the Emperor, so all Darth had to do was let him, and maybe lend a helping hand, a proposition he gave to his son one movie earlier.
    – JMD
    Commented Jul 19, 2012 at 15:48
  • Maybe he was subconsciously trying to prevent his son from falling to the dark side :)
    – Ryan
    Commented Jul 19, 2012 at 17:13

This topic has has long since ended discussion, but to throw my two cents in.

Remember that Vader is not redeemed yet. He is still very much the ruthless character of Empire Strikes Back. Vader in Empire Strikes Back wants Luke to join him so that he can overthrow Emperor Palpatine and make himself ruler of the Empire. He remarks "perhaps you are not as strong as the Emperor thought" because he is coldly evaluating whether or not Luke is as useful to him as he had hoped. Vader cut off Luke's hand and growled "don't make me destroy you". He is conflicted in that part of him merely views Luke as a tool to overthrow the Emperor, while at the same time genuinely wanting Luke to be at his side.

Vader is obviously tempted by bursts of rage to kill Luke but he is also constantly coldly evaluating Luke. So why did he block the "death blow" on Palpatine, one: Palpatine never really intended himself to be sacrificed, he would have used the force to stop Luke's lightsaber and redirect the fight to Vader and Luke regardless. Vader knew this,

Vader believed Luke's anger was not strong enough to be able to kill Palpatine yet with the Dark Side despite Palpatine's efforts to anger him. Palpatine does not have as strong of a link with Luke's mind as Vader, but he found Luke's weakness of attachment to his friends, which Vader builds upon. Vader intended to enrage Luke by finding Luke's deepest fear, which was that if he could not be turned to the Dark Side that Vader would turn Leia to the Dark Side. Vader believed he could hold off Luke's rage and attack and then when Luke's rage was at its purest, turn Luke's rage to kill Palpatine.


Well in that moment the Emperor said:

"Good. I can feel your anger. I am defenseless. Take your weapon. Strike me down with all of your hatred, and your journey towards the dark side will be complete." source

Vader did not want his son to fall to the dark side. It was the first sign of actual conflict.

  • 1
    The Emperor knew Vader would defend him.
    – Neal
    Commented Oct 31, 2015 at 22:07

Well, in the original Star Wars 6 book, Vader says, "he could have allowed Luke to destroy the emperor, but Luke was simply not ready for that yet, emotionally". Meaning If Luke had killed the emperor, he would either go back to the light side, or kill Vader there and then. Vader also says, "To bring Luke to the dark side, he would NEED the emperor's help". So Vader couldn't allow his son to destroy the emperor


He says to Luke “You already have Luke… You already have,” thus knowing he proved to Luke and himself he had good in him So Darth Vader didn’t want Luke to turn and become evil much like what he had become. Darth Vader loved his son and it was clear in The Empire Strikes Back: “Son come with me.”

Also it was the conflict arising within him..... Part of him wanted to obey his master and have his son turn to the dark side.. The other part wanted him to stay as was

“It is pointless to resist my son”..... Not the words of an angry person but more someone feeling defeated.

Another example of Vader protecting his son was letting the fleet through.... “Where is that shuttle going?”..... He chose to allow them through: “Are your feelings clear on this, Lord Vader?”

Vader could have taken the Emperor on.... He was more powerful and it was why the Emperor made him more machine to control him. But he couldn’t control his heart.


I suspect Vader never believed Luke could win. Palpatine was far from helpless after all.

Taking that further and considering the Rule of Two, it's possible Vader is resigned to the fact that Luke will either have to kill him or die. I kind of like the idea that Vader chose to fight his son and throw it to save his son's life rather than kill his son.

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