(A/N: This is set near the end of Into Darkness. I'm definitely no expert on TOS and I don't remember the exact words of the scene, but I've tried to capture the idea of it.)
Spock was crying.
Thoughts came to Jim in odd eddies, drifting closer and pulling away on a tide, but they kept coming back to that one fact; that one, undeniable, illogical truth.
Spock was crying.
It was hard to focus. His mind, and his eyes, kept sliding away from the world, blurring and dimming. There was so much – so much to say, so much undone, but his lips moved soundlessly.
The glass was cool against his feverish fingers, and he imagined that the soothing feeling came from the hand on the other side. If he had been afraid of anything, if one thought had driven him as he crawled along, dragging himself back towards the rest of the world, it had been fear for his crew. Had he done enough? Had he failed them again? But they were safe. Spock had said it, and Spock would not lie; his crew were safe.
And yet there had been another fear. If he could admit it to himself – and what, he thought dimly, could he not afford to lose now? – he had been afraid of dying alone.
But there was a hand pressed on the other side of the glass.
He owed Spock. For everything, even if the Vulcan didn't realise.
"I want to tell you," he said, forcing out the words, even as his body failed around him. Everything hurt, so much more than he could have imagined; breathing felt like it was killing him, but some things were worth dying for. "Why I couldn't let you die."
Spock knew. Oh, he had to know, didn't he? Jim's breaths were shallow now and his head felt like it was on fire, but he would not give up yet. After all, living was harder, Jim knew that. He had to give Spock something that would help, and Vulcans liked the truth.
And it was true. Jim wasn't quite sure when it had happened; when the creature that had almost killed him, the robot, had begun to mean so much to him. Khan had called it family, and he was right. It was family, of a kind Jim had never really known, the kind of family that he could love and hate and forever argue with, and would lay down his life for. He had laid down his life for it. Though it hurt, though he could no longer move enough to curl up or find the energy to scream, although it was worse than he had ever known anything could be, it was worth it.
These lives, and this friendship, were worth it.
He had to make sure Spock knew that before it was too late.
Jim watched the tears run down Spock's cheeks, and he saw what he should have known all along.
"Because I am your friend."
He knew. He knew, and Jim found himself smiling. He knew, and there were no more words to be said.
Jim didn't give up. He didn't give up because James Tiberius Kirk never gave up, and he never admitted defeat. He had thought, not so long ago, that he had lost everything. But this, here and now, was not a no-win situation. He was dying, but that wasn't the same thing as losing, and that's what no one had ever understood.
His crew – his friends – his family were safe. He had kept them safe.
And there was, he thought, in the seconds before his heart stopped beating, no greater victory in all the universe than that.