She reminded him of Padme, and it killed him.
The bravery, the diplomatic approach, Princess Leia even looked like her. Though she didn't act like Padme, not exactly. She didn't bother to hide her hatred of him, of Tarkin, or anyone else onboard. She didn't have the kindness and he knew as he escorted her back to her cell after watching her planet be destroyed that she didn't forgive. She never forgive the Empire for that. Vader had felt the cries of the souls through the Force, felt the Dark Side energize from it, and he wasn't sure they would have deserved her forgiveness.
She may not have been exactly Padme, but he still constantly got flashes of his lost beloved when he was around this girl.
When it had just been him and her, alone with the space droid probing her for information, it almost felt like she was forcing images into his mind with the power of the Force. Flashes of Padme in pain, laying in a white room.
Obi-Wan was there, holding a baby.
That was when the anger took hold. Obi-Wan had taken everything from him. It may have been a mercy to have killed his beloved if just to ensure that she didn't leave him for his former master. If just to make certain that his son never called Obi-Wan Kenobi father.
It had been easy to finish the torture after that.
Leia hated him.
As Darth Vader's stooge deposited Han back into their cell, she rushed over to him. She was too worried for him to bother trying to hide her feelings for him. She'd been at the end of Vader's torture, and knew the pain that Han had just suffered.
"They didn't even ask me any questions."
That was strange. She cradled Han closer. Chewie was saying something, but even after three years together, Leia could only pick up a few words of what the wookie was saying. Something about Vader and Luke.
She wondered if she was next. She guessed that if Vader was after Luke, she'd be used as bait for him. They were handing Han over to the bounty hunter, so she guessed that Vader didn't care about his condition, but she would be kept alive.
The guards got them, forcing them to a room with the carbonite freezer. The entire scene played out like a movie.
"I love you."
"I know."
She hated that her worst enemy had been present for the only time she had confessed her love aloud. She hated everything about Darth Vader and how he was single-handedly destroying her life.
He'd taken Han, and now he was after Luke.
Sister?
Luke had a sister?
Who?
Vader searched his child's feelings, but the anger had taken control. He knew what happened next. When you fell to the Dark Side, you became almost unstoppable. He could barely keep up to block every blow, and was forced onto his knees.
It was over then.
But then…Luke did something that he had never had the courage to do – he refused Palpatine. He stepped back from the abyss that was the Dark Side. Darth Vader had convinced himself that it was too late, he'd gone too far into the Dark Side.
His thoughts swirled with all of Luke's words. Of redemption, of believing in him…Luke reminded him of his wife. He took after her so much.
Just like Leia had reminded him of her. Vader knew that his son had grown close to the Princess since their escape. He had felt Luke call out to her at Bespin.
And she had answered.
Sister, Luke had a sister. He'd been a twin.
He knew. Leia was Luke's sister. Princess Leia was his daughter. And what had he done to her? Oh God…
His boy cried out for him, bringing him back to now.
He couldn't fix the past, but he could fix this.
He could stop this.
His child was in pain.
