Robitcs.
Electronics.
Building things.
Before he became Darth Vader, he had a talent in all three. He could remember when he built a droid to help his long-deceased mother, his first lightsaber, and how to repair a damaged circuit in a droid. If something went wrong in one of his robotic limbs he was quick to fix it.
No one else was allowed to help him. It was either him or machines.
Machines helped him with his armor, but with his artificial limbs, he fixed them by hand.
Vader had a room that he used when he was designing weapons or fixing a glitch in one of his robotic limbs, but behind one of his machines was a hidden doorway that led to a small room the size of an operating room. It had three computers, an operating table, droid parts, tools, a memory insert, and a droid stand.
The day the Death Star was completed was the day Darth Vader moved his equipment into both rooms. The extra room was requested by Vader, but no one else knew why except for one of his droids, Q-4PA. Vader had set up both labs: one for repair and design, and the other to fill a painful, empty void.
It had been a few years since he lost Padmé, but he was still grieving and felt guilty for killing her. He wanted to bring her back, but he couldn't by trying to raise her from the dead. His only conclusion was to use his skills in robotics and electronics to recreate his beloved wife.
The first thing he did was extract her memories from her brain, but there was one problem: he didn't know where her grave was. Fortunately, he knew how to get into the Naboo files to find birth and death dates of the citizens who lived there. After searching her name, Vader found that Padmé's tomb held her body inside the Queen of Naboo's palace. Before he arrived, Vader disabled all security for a certain amount of time to allow Padmé's memories to be extracted into a memory file.
Vader only took the happy memories of the two of them, what she remembered from her childhood, and who she was as a person.
He left out the memory of being choked by him.
Successfully, he was able to leave the planet with the memories without anyone else knowing he was there.
Next was to gather droid parts to build the body. He knew he couldn't just disable and dissemble droids on the Death Star. Instead, he would take droid parts still in working condition after a battle occurred. That part took a few moths to complete, but it was worth bringing his lost love back.
Now that she was assembled and made to resemble Padmé by using holographic technology, he placed the expressionless droid on a chair, set a helmet like device over it's head, and began to insert her memories. As the helmet did so, Vader commenced to remove his mask with another machine and place a clear breathing mask over his nose and mouth. He wanted Padmé to see him as the man she knew and loved before, Anakin Skywalker. There was a chance she wouldn't recognize him from behind his burned and scarred face, but he knew deep down that she would know who he was.
Just his breathing mask was placed on, a chime sounded to alert Vader that the insert was complete. His weak heart began to pick up its pace as he removed the helmet from Padmé.
Small head movements came from her as if she were searching for her memories in a dark abyss. Vader stood in front her, and Padmé began to open her eyes. When she focused her gaze upon him, there was a pause.
Everything seemed to stop for a moment. Vader began to wonder if he did something wrong or a wire had come loose.
All of a sudden Padmé threw her arms around Vader, and he knew he could finally have her back.
"Anakin," she whispered his real name.
He sat Padmé on the operating table, kneeled in front of her, and begn asking questions to make sure she knew who she was.
"What is your name?" he asked.
"Padmé Amidala," she answered with a smile.
"What was your occupation?"
"Senator of Naboo."
He continued asking questions for about an hour just to be sure she knew who she was.
After she answered the last few questions, Vader sat next to his beloved wife and took her hand into his; she rested her head on his shoulder.
Vader smiled.