Leia Organa has been on Darth Vader's radar for a long time.
There's something about her that sticks in his throat. It makes little sense; before her involvement with the Rebellion she was little more than an outspoken Senator-- someone for the Emperor to deal with, not his responsibility. He's almost glad that she turned away from the Empire so that he has an excuse for his focus.
She looks like someone he knew long ago, in a dream. He doesn't think about that. He tries not to think about that, but it creeps in sometimes when he's in his room, staring at the stark white walls and trying to relax. He meets a lot of ghosts in that room. It's better to keep his eyes shut.
When he finally boards her ship and the princess stands in front of him, defiant, he feels her rage rise up around him and he embraces it. He breathes in hard. Finally, he is going to figure out why she has come to his attention. Finally, he will understand his fascination.
But he doesn't. He has the interrogation droid, but she laughs, spitting blood in his face. It slides down his mask.
"Ask me again," she says. "I'm not going to tell you anything."
"Resistance is futile," he answers. She grins at him.
Eventually, there's a knock at the door. He starts out of his reverie. The interrogation droid beeps a question.
"Did I tell you to stop?" he says. The door shuts on her scream. Tarkin is standing outside.
"Sir," Tarkin says, and then nothing. Vader counts two long breaths.
"Yes," Vader says finally.
"Has she broken?" Tarkin asks. Vader shakes his head.
"I have an idea, sir," Tarkin says, and when he explains, it is too perfect for Vader to say no to.
He wants to know what she will do when all her hope is gone.
He doesn't go back into the chamber. The stormtroopers escort her to the bridge. She trades quips with Tarkin as if she hasn't just spent hours in agony. Her spirit is undiminished. Tarkin takes a step forward, and he takes a step forward, and when Leia gives in, she is pressed up against him, shivering with anger and fear. There is nowhere for her to go. He will understand her now.
When the Death Star fires, Vader's hands are on her shoulders, and he squeezes hard. She cries out. In the Force, there is a cut-off scream, a sudden aching silence. He breathes in.
She passes out. He's almost disappointed -- fainting seems beneath her. She endured so much at his hands already, and this didn't even affect her directly. He lets her slide to the floor, noticing that she is clutching her hands into fists even now.
"Take her to the detention wing," he says, and the stormtroopers do, but he feels her still, all the way across the battle station. His sleep, always uneasy, is full of terrible memories.
It's not until much later that he realizes who she is.
"A sister," he says. "A sister--"
He sees Luke's face contort in rage and lets him come, raising his lightsaber to counter. He can turn her, he thinks -- he remembers her anger, just the same as his own --
But no. It is all Padme's, frustration and worry over planets of people she can't bear hurting. It is not his own selfishness, his terror of loss. She's better than that.
And for just a moment, he is proud.