Okay, so, disclaimer - no one here belongs to me. The dialogue doesn't even belong to me.
This is all written from the POV of Spocktimus Prime, aka the "old" Spock from Star Trek (2009).
His thoughts outside of the dialogue, however, are my own words. Also.... heavy K/S suggestions!
It's not fanon - it's canon!
Meeting Kirk's Counterpart
I gazed at young James Tiberius Kirk with old, weary eyes. The fire from my torch being the only light in this dark, dreary cave. "James T. Kirk…" I could hardly believe it was him…
He gazed at me in disbelief, panting from his previous excursion. He had been running from something – I couldn't exactly say what at the moment. My world was spinning out of control. "Excuse me?" he said.
"How did you find me?" I wondered.
He stood warily, the disbelief still in his eyes. Oh, Jim… You were always so theatrical, I thought. "Whoa, whoa, whoa. How do you know my name?"
I thought of my words carefully. For Kirk to not recognize me, and indeed it felt as though the bond between us had not yet occurred, I could not refer to him as anything more than… "I was and always shall be your friend."
"What?" He shook his head, laughing slightly. "Look. I, uh… I… I don't know you."
"I am Spock." And the look on his face made my half-human heart, already battered by the loss of my home planet, weep.
"Bullshit," he said and my eyes closed. Explanation would be needed.
Soon enough we were sitting around a fire together and I could almost imagine that I was with my Jim. My T'hy'la had been gone for many years, yet I still felt him in my heart… To see him now… I yearned to hold on to him, but the young man he now was would not understand. They both needed time… They both needed to find their places in the world. "It is remarkably pleasing to see you again, old friend. Especially after the events of today."
"Uh…" He rose. My heart sank further. "Sir, I appreciate what you did for me today, but if-if you were Spock, you'd know that we're not friends. At all." He was wrong. We were the greatest of friends. "You hate me," Jim continued. "You marooned me here for mutiny."
"Mutiny?" I could not believe my ears. "You are not the captain?"
He struggled with his words a moment. "No, no. You, uh… You're the captain. Pike was taken hostage."
And I realized it: I had made a grave mistake in my own timeline and now… Now it seemed this timeline's version of me was making even greater ones. Not very logical ones from the sound of things. They would not lead myself and this Kirk on the paths they were meant to take.
He turned slowly, lips parted. "What do you know about him?"
"He is a particularly troubled Romulan." And if Jim and my obviously confused self were going to stop him, Jim needed all of my assistance. I rose and walked towards him. "Please, if you will allow me, it will be easier."
He backed away from my outstretched hand. "Whoa, whoa. What're you doing?"
"Our minds." It was difficult to keep my voice steady. "One and together." And I placed my fingers to his face in a move that was as familiar to me as it was unfamiliar to him. I would have to be careful to keep track of the information I needed to give him…
My mistake needed to be revealed. "One hundred twenty-nine years from now, a star will explode and threaten to destroy the galaxy. That is where I am from, Jim: the future." And I seeped into his mind so that he could see all that I had done. And, more importantly, had not done.
"The star went super nova, consuming everything in their path. I promised the Romulans that I would save their planet. We outfitted our fastest ship. Using red matter, I would create a black hole that would absorb the exploded star. I was on route when the unthinkable happened. The supernova destroyed Romulus. I had little time. I had to extract the red matter and shoot it into the supernova.
"As I began my return trip, I was intercepted. He called himself Nero… the last surviving Romulan… As I attempted my escape, both of us were pulled into the black hole. Nero went through first. He was the first to arrive. Nero would spend the next twenty-five years waiting for my arrival. But what was years for Nero… was only seconds for me.
"I went through the black hole. Nero… was waiting for me. He held me responsible for the loss of his world. He captured my vessel and spared my life for one reason: so that I would know his pain. He beamed me here so that I could observe his vengeance. As he was helpless to save his planet, I would be helpless to save mine. Billions of lives… lost… Because of me, Jim! Because… I failed."
The meld ended abruptly as it wasn't the young Jim I was speaking to any longer, but it was my own… The one that had passed on several years ago, his hand in mine.
The young Jim panted as the meld broke, his own mind swirling – I am sure. Had he felt my deep sorrow? My deep love? "Forgive me," I said. "Emotional transference is an effect of the mind meld."
He staggered away, breathing heavily. "So you do feel."
"Going back in time, you changed all our lives."
"Jim…" I knew that… I could never apologize enough for it. "We must go." He turned back to me. "There is a Starfleet outpost not far from here."
"Wait." I glanced back. "Where you came from… did I know my father?"
I could not lie to him. "Yes. You often spoke of him as being your inspiration for joining Starfleet." What, I wondered, had been his inspiration this time? "He proudly lived to see you become captain of the Enterprise."
"The ship we must return you to as soon as possible." I knew myself well enough to know that I was an unsuitable captain. Longing for the future I had left behind, I strode off.