"What do you mean, it's unlikely to be cured? Is It Terminal?"
"I'm afraid so, Mr. Kirk. "How long do I have?"
"With treatment, perhaps a year. Without, maybe six to seven months."
"Your vitals are way off!"
"Get that thing off of me, Doctor."
"You're a mess, Jim."
"I'm Fine, Bones."
"The Hell you are!"
These conversations rang through Jim Kirk's mind as he climbed through the tunnel that led to his ship's warp core. So much had happened in the week since his diagnosis, that he had pushed it to the back of his mind.
Pike dying, chasing Khan, fighting Klingons, and being hunted down by Marcus all served to distract him from the grim news of his own impending demise. Jim hadn't told anyone, not even his best friend, because he could hardly believe it himself and he really dreaded seeing the devastation that the news would bring to the man who had been there for the rough times and good.
Jim ached all over as he laboriously climbed up the core. He didn't know if it was from the disease ravaging his body or the radiation poisoning breaking him down. The symptoms of the rare disease (he couldn't pronounce the name, but it was something alien) had begun to be difficult to hide and the sharp-eyed Bones had noticed something was wrong when he ran his tricorder over the captain on the way to the Enterprise.
Kirk had dismissed him before he could look any further. He was going to get Harrison, dying or not.
"At least this way it won't be long drawn out death and nobody will have to see me waste away", he thought, gritting his teeth and kicking the misaligned parts over and over with every ounce of energy he had left. The fight with the Klingons had left him doubled over with exhaustion, even coughing up blood. He had known then he couldn't hide it much longer.
The Core housings sprang back in place and Kirk was propelled backwards by the blast of energy. He hit the ground hard and blacked out briefly.
When he came to, he began a halting, painful journey back to the door he had entered after knocking out Scotty. He had to stop several times because of the pain and nausea, which led to violent vomiting. Jim was completely exhausted and wracked with agony by the time he collapsed against the chamber door. He knew he wouldn't last much longer now, but
maybe he could at least say goodbye to Scotty. The poor man looked wrecked, seeing his Captain suffering and unable to do anything.
Spock arrived in a rush and knelt in front of the glass. Kirk's head was so fuzzy, he couldn't focus on much after the Vulcan assured him the ship was safe. He had done his job and now he could die in peace. With his last words he tried to make Spock understand how he valued their friendship too much to let him die-first in the volcano and then in a plummeting starship. It appeared Spock got the message when he matched Kirk's hand on the glass in the Vulcan farewell. But as Jim felt the life leave him, his last thought was, "I'm so sorry, Bones."