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[Star Wars] What are Darth Vader’s motives for doing the Empire’s dirty work following Padme’s death?

Anakin/Vader is one of my favourite characters of all time but I always felt a disconnect between the Vader we see at the end of Episode 3 getting put in the suit vs the Vader we see at the start of Episode 4 enthusiastically carrying out the Empire’s dirty work. 

When Vader is told he’s accidentally killed Padme at the end of Revenge of the Sith he seems like a pretty broken man, literally and figuratively. He sold his soul for the power to save the love of his life only for his powers to kill her in the process. Now he’s done horrible things and is barely alive, and obviously heartbroken. 

The next scene hes watching the Death Star getting built, and the way he crosses his arms almost gives me the impression of satisfaction? And then in A New Hope he’s out acting as an enforcer for the Empire. 

If I were Anakin waking up in that suit, I think I would be pulling a Padme and simply lose my will to live. Or I’d put a lightsaber through my head. What happens between the events on Mustafar and finding out about Luke that the only reason for him existing is for him to carry out the Empire’s will? 

I haven’t seen a lot of content besides all the movies and some of Clone Wars so let me know if there’s something that explains this in anything.
gpt
The 2017 Darth Vader comics cover the transitional period between three and four.

A decent chunk of it was him having the opportunity to take out his anger and lingering resentment on various Jedi who escaped the purge, many of whom he maintained grudges against from his time as Anakin. He also finally, *finally* had the absolute authority to beat in the head of any civilian, politician, trooper or bureaucrat who he saw as letting their flaws and/or personal agenda get in the way of finishing the job. For Vader- a dark, twisted reflection of Anakin- that was more important than what the job *actually was.*

Towards the middle of it, he also had the carrot of possibly being able to use the dark side to ressurect Padme, although that went about as well as anything involving the dark side does.

Lastly, he found out about Luke much earlier in the Disney Canon than he did before; he was plotting to overthrow the Emperor almost immediately after Yavin, and had Luke as the light at the end of the tunnel for a few years before Bespin.