He wanted to take over the empire, it would literally change nothing, he would still be a sith lord and would just have Luke as a sith on his side as well.
HOLD the heck up, son, you're about to get knowledge all up in this thread.
Vader didn't want to kill the Emperor because he was good. He wanted to kill him so he could become the next Sith lord. See, waaaaaaaay back in the days of the Old Republic, the Sith weren't just a master and a apprentice, they were an entire order, just like the Jedi. However, due to the nature of the Dark Side this resulted in a bunch of infighting, rather than combating the Light Side.
Thus, Darth Bane tricked the rest of the Sith into offing themselves and initiated the Rule of Two: there would only be two Sith. The master would rule as Lord of the Sith until the apprentice had learned everything they could from the master, and became strong enough to overcome them. This would ensure only the most powerful and ruthless of the Sith would be in charge, and it would also ensure that the Sith would continue to grow in their knowledge of the Dark Side.
Whenever the Rule of Two has been usurped, it always ends up harming the Sith. For example: Darth Malak never fought his master, Darth Revan. He simply betrayed him to the Jedi so that he could become Lord of the Sith. This resulted in Revan turning back to the Light Side and royally kicking Malak's ass. Palpatine was also usurping the Rule of Two, but in a less obvious way. His reconstruction of Vader left him as a shadow of the man he once was. He was a brutal enforcer, to be sure, but his cybernetic implants and limbs greatly weakened his connection to the Force. Palpatine purposefully kept Vader like that because he knew that Vader wasn't strong enough to challenge him.
Thus, Vader's attempts to turn Luke (and earlier, his attempts to train his own apprentice, Starkiller) were him attempting to overcome the power imbalance between him and Palpatine. Ironically enough, I'm pretty sure it was Palpatine's efforts to stay in power that resulted in Vader turning on him in the end. Had Palpatiene helped Vader reach his true potential, and had Vader killed Palpatine to become the Sith Lord, I'm pretty sure Luke wouldn't have been able to turn him back to the Light Side.
In Episode III Darth Pope Benedict lied to Anakin, claiming he killed Padme.
When he found out his son was alive i'm sure he got pissed off and wanted nothing more but to get even with the emperor.
So i he wants to team up with his son.
I actually have no idea what i'm talking about, get off my back i just wanted to make a political reference Also, tell me more about Darth Bane Why does he wear the mask?
That's dropping a lot of >implying.
First, you have the second Death Star was being constructed. There's a good chance that was probably going to be used with the same care as the first one. Even if it was used only once to destroy another planet, that's still way more lives lost than if Luke continued to resist his father and the dark side.
Second, there's a pretty chance even if Luke and Vader were able to defeat the Emperor, they'd do it to simply continue the Sith line. Luke didn't have any of Yoda's training, so he'd be even more vulnerable to the dark side than in the Episode VI where he noticeably falls to his emotions, even for just a moment. Considering Vader was considerably more full of untamed wrath than the Emperor, there's a solid chance the second Death Star would be used even more frequently under his power than under the Emperor's to boot.
More lives would defo be lost if Luke went baddie.
Mark Hamill did play the trickster and used the same voice acting for that character as he did the joker. But the lines could be from anywhere he has been doing it awhile.