This is my last Xtober ficlet, I believe! Originally written for Whumptober Day 26: If You Thought The Head Trauma Was Bad...

Luke bowed deeply when he entered the room, so low it made Vader uncomfortable. He had intentionally left his son, the boy he'd protected and raised, with Palpatine for a year while he defended the Death Star, it was true. And he knew that Luke was loyal to him—the fact that this coup was going ahead as planned only proved it. But he still didn't like seeing his son grovel before that man.

Not when his son would be a prince soon enough, and be required to bow to nobody.

"You are both returned from your sojourn on Mustafar, then?" Palpatine asked benevolently, gesturing for Luke to rise. Vader rose from his kneeling position as well, before Palpatine tutted sharply.

Vader froze.

Palpatine turned back to Luke, and made the gesture again, pointedly. It did not encompass Vader.

That… seemed odd.

Luke stood to his full height, shifting into parade rest with his hands behind his back. Palpatine looked at him approvingly, as did Vader. He could sense his son's apprehension—no doubt he could recognise the oddity in Palpatine's behaviour as much as anyone, and what it meant for their plans—but Luke was holding himself together well, under Palpatine's scrutiny. He was so brave.

"I trust it was restful?" Palpatine addressed him gently. Luke nodded sharply, sensing that words of affirmative were unnecessary, and Palpatine smiled with yellowing teeth. "Good. You worked so hard for me this previous year"—worked so hard executing people for him, Vader knew, had seen Luke's haunted eyes; spying on courtiers for him; assassinating and intimidating and running errands; acting as Palpatine's personal Force-sensitive pet—"you deserved it. And I hope you are prepared now to serve me again?"

Luke patted his lightsaber at his hip dutifully. "Yes, Master."

"Good." Palpatine smiled, then inclined his head to Vader. "Then the time has come. Kill him."

For a moment, Vader couldn't breathe—couldn't move.

Luke snapped his head up, eyes wide. "What!?"

"It is your destiny, remember, Luke?" Palpatine's voice had taken on a chiding quality, a soft warmth, like a grandfather cajoling his favoured grandchild. Vader was only present enough to process that he hated him manipulating his son like that before he surged to his feet, drawing his lightsaber—

Lightning flashed and pain seared.

He thunked to his knees on the floor. His organs seemed to shriek in a harmonious cacophony, the world blooming red around him.

"I would recommend you stay down, Lord Vader, and it will be easier for everyone," Palpatine sneered. Then, to Luke: "Kill him."

"No!" Luke was staring at Vader, hand fisting on his lightsaber hilt, but he made no move towards him. "No, I— why would I—"

"You told me yourself, Luke. He was about to turn traitor."

What.

All the blood roaring in Vader's head crashed to a silent standstill.

What.

"He was about to kill me. You know the punishment for treason like that, child. He has to die."

Vader and Luke had come here to overthrow the Emperor. To kill him. Of course it was possible that Palpatine's vaunted foresight could have warned him of it, but…

He had already known?

And— and Luke had told him!?

Vader, every individual vertebrate in his neck flashing with pain, turned his head inch by inch to look upon his son's face.

The absolute horror—and guilt—that called it home.

"Luke?" he whispered.

He'd left his son alone with Palpatine.

For a year.

Of course that had done damage that was not at first clear.

Of course that had—

"You said you would leave him alive!"

Vader closed his eyes.

Luke.

Oh, Luke.

"He is willing to kill me, Luke. Why would I leave such a threat alive? You understand the danger he poses—that was why you confided in me to begin with. Kill him."

"No!"

Palpatine raised his hands—they sparked dangerously. "Do not make me discipline you as I would a traitor as well, Luke. I know you are no traitor, I know you are loyal, but—"

"I won't kill him. You promised."

"You will."

Palpatine stepped closer to them both—no, to Vader. Vader, on his knees, staring up at his master's sagging face.

"And if you do not," he intoned, "I will."

Lightning flashed again.

This time, Vader flew right back—he was thrown against the floor so hard his head cracked against it, his vision blurred. For a moment, he blinked and there was nothing but darkness.

Then he opened his eyes again, a few moments later, to several things: the sound of more conversation, buzzing beyond his comprehension; yellow Aurebesh scrolling in front of his eyes from his mask, indecipherable; a bone deep ache everywhere in his body, including his stomach. Nausea roiled when he made the slightest movement to try to sit up.

But one thing stood out:

He was not dead.

Luke had betrayed him. Palpatine had shot him with enough Force lightning to short his suit out a thousand times—but it hadn't.

It wasn't supposed to. Vader had had it modified for the coup. But… Luke had known that.

Luke had known that—and hadn't told Palpatine.

Luke…

Luke was standing right in front of him, and his hands held a beam of bloody light.

"No," he hissed, voice choking with tears. "No, please, Master, don't— don't hurt him, don't come any c—" He sucked in a breath, shaking.

Palpatine said, "Oh, Luke. I understand you are attached, but…" He took a step closer.

Luke took a step back, his heel bumping into Vader's foot. "No! Stay away from him! I— I won't let you."

Palpatine grasped his white hand around Luke's, gently, and turned the lightsaber off.

"Luke, it is time you shed your father. Allow the Force to claim his life to make way for the strong, as it always does. I have told you many times this last year, I look forward to the day I can officially have you as my apprentice."

"No. No, please, leave him—"

"This is an important tie to sever. This is an important moment in your ascension to full Sith. It is time you took destiny by the hand and walked the path that was ordained for you, to greatness."

Still with that tight grip on Luke's wrist—Vader's angle was strange, his vision blurring even more, but he thought he saw his nails break Luke's skin; rage trickled in—Palpatine tugged Luke forwards.

Luke, boneless and broken, didn't resist as he wrapped his arms around him in some semblance of a hug.

Luke was shuddering. His shoulders were wracked with great sobs, his knees weak; he was half-leaning on Palpatine to stand up. Palpatine rubbed circles on Luke's arm, his shoulder, murmuring things Vader could barely hear.

And then, over Luke's shoulder, he smiled at Vader.

Smug, deadly, self-satisfied.

He knew he had won.

Once again, he had torn Vader's most precious thing away from him—destroyed it, and made it his own.

He pulled back from the embrace, still leaving Luke a shaking mess to stand on his own. He came back closer, holding his wrists, wrapping Luke's hand tightly around the hilt of the lightsaber once more.

"Now, my young apprentice," he whispered, and there was a glee in his voice. "Are you ready to do what must be done?"

Luke's shoulders stilled. Stood firm.

Luke took a deep breath.

Vader closed his eyes in preparation for the final blow.

"I am ready."

The snap-hiss of the lightsaber made him flinch anyway, the red light of two strokes—two savage, precise strokes—filtering through his eyelids to herald him into the arms of death—

But no burning came for him.

There was a thump.

Vader pushed himself up to his knees, head spinning and really kriffing hurting, then blinked at the sight before him.

Luke stood, jaw clenched, face grim.

Then he turned back to his father, and the grimness melted into something a thousand times more tender. "Father, I—"

"You killed him," Vader marvelled. Two strokes, to sever him into four pieces, from what he could tell—Luke had taken off his hands, then his head, in two brutal, graceful strokes.

"He knew about the coup already—months ago." Luke swallowed. "I— I tried to play along, tried to make it seem like I was on his side—"

Luke was trembling again, face crumpling, his lightsaber falling to the floor. Vader shoved himself to his feet just to make the two-stride motion to seize his son around the shoulders, to catch him before he collapsed. Two unsteady ships weathering the starstorm together.

"You succeeded," Vader said softly, brushing hair back from Luke's face. "He is dead. You may have gone every so slightly off plan…" Luke managed a weak chuckle, though even that brought faint tears to his eyes. "…but it is of no consequence. You succeeded, son. You killed him."

"And you were hurt."

"I will live, Luke." Vader cradled him against his chest like a newborn, tilting his head up to behold the empty throne, the red and black sliding and crumbling together. He still couldn't see well, but perhaps he could see better than ever: when he looked at Luke's face, the lights on his hair eclipsed it with a halo. "We will both live."

He glanced back at the throne again and was already thinking about how to make it more suitable for his son. "We will rule.

"He will hurt us no longer."