What were Vader's plans...?

In ESB, Vader first tells Lando that Leia & Chewie were to "never again leave this city." When he later alters the deal, he tells Lando, "Take the princess and the wookiee to my ship."

What was Vader's purpose in leaving the two on what amounts to house arrest on Bespin? And what did he plan to do with the pair when he got them back to the Executor?

 

He was trying to get Luke to come to him. they were bait.

 

I agree that he drew them to Cloud City as bait, but if he believed Luke would come, why all the specific (and cryptic) plans for Chewie & Leia? "They must never again leave this city" really has nothing to do with their use as bait.

 

He didn't trust Lando.

 

I think you see the genious in Vader here.

He NEVER intended on leaving Leia and Chewie on Cloud City, he was just bating Lando into helping him. And, when Vader got what he wanted- he switched plans on Lando- full knowing there was nothing Lando could do about it...

What he would do with them on the Star Destroyer was probably probe them, after he got Skywalker, to find the rebels...

 

I don't know if I'd call it genious so much as just bullying Lando. Vader could have done everything by force from the get go, but it's so much easier if the people help you willingly! He can make Lando any sweetheart deal he wants and it doesn't matter if he just threatens to kill him for not going along with the 'new' deal.

 

Genius. Pure and simple.

He told Lando what Lando wanted to hear...in his mind, he wasn't turning his friend Han into the Empire, he was only helping trap some stranger named Skywalker while protecting his people on Cloud City.

Vader used a con man's trick of leading the dupe on.

 

"Pray that I not altering the deal any further!!"