Major spoilers for His Last Vow.
Also, my deepest apologies on not updating my other fics in a while. I'll get right on it.
It's just that this could not wait.
Sherlock stood in front of John on the tarmac. A gentle wind ran through his curls and ruffled his hair. He took a breath. He was leaving on a mission that Mycroft said he wouldn't survive from. Sherlock happened to believe him. Mycroft hadn't wanted him to take this mission, but there was no helping that now.
John Watson stood in front of him, trying to hide his sadness. Sherlock had told him he was leaving and where he was going, but left out that he was nearly certain to die. He only mentioned that they wouldn't be seeing each other.
"Since it's unlikely that we'll ever meet again," Sherlock began, "I might as well say it now."
Sherlock's mind scrambled for a way to sum it all up. He rejected idea after idea.
You are one of the bravest men I've ever met.
Thank you for being my friend.
I hope you and Mary are very happy together.
You've been by my side for so long and I missed you so much while I was away for those two long years. I had no idea you'd be so affected by my death. Please forgive me. I'm so sorry I have to leave again.
COME WITH ME.
I did all of this for you, all of it. Your happiness is what I want most.
You're beautiful.
John, thank you. You've bravely stood by my side all these years. You're important to me. You matter. You've been the light in my darkness for so long.
I didn't know I needed you until I met you and I know what's it like to live without you and I don't want to do that again.
I never really minded that you forgot to get the milk.
John Hamish Watson, I love you. I love that you aren't afraid to get angry with me. I love that you care. I love your funny-looking jumpers and your willingness to rush headfirst into danger for me and your trust and faith in me even when everyone else thought I was a liar. I love your smiles and the way you laugh.
(and now it's too late too late too late)
In the fraction of a second, all of that went through his brain.
I love you, John, he shouted, but the walls of his mind palace locked his screams away in a split second as he lost his bravery.
"Sherlock is actually a girl's name." Sherlock said, putting on a small smile.
John laughed, looking away for a brief moment, and Sherlock's heart ached.
Sherlock continued to say things to John, thinks he truly felt but it wasn't enough, and John said things, too, things Sherlock couldn't focus on.
They shook hands. Sherlock wanted to pull John close to him and never let him go, but he didn't. He restrained himself.
As he climbed into the plane and took his seat, he felt an aching loneliness creep through him and seep into every square inch of his body. He stared out the window at John and Mary, who looked so happy. Not happy because he was leaving, thank goodness, but just happy because they were together. It hurt. It hurt so much. He'd not told John he loved him years ago, and now it was too late. The man he loved had fallen in love with someone else, and there was nothing he could do about it now.
When Mary had been revealed to be a traitor, Sherlock had allowed himself a moment of irrational hope. John would divorce Mary. John would spend more time with Sherlock. Sherlock would propose, John would accept, they'd be happy together, no Mary no Mary no Mary.
But no, John still loved her. He wanted her to be happy. And Sherlock would be damned if he couldn't make John Watson happy. He'd come up with the plan to stop Magnussen- but, well, that had been a bit faulty. Not because he was a bad planner, but because he'd underestimated Magnussen.
But all had turned out okay for the Watsons. Not for Sherlock, but for the Watsons. And that was all that mattered.
(right?)
The plane began to take off. Sherlock felt bleak. His eyes were dull and his expression blank. What was the point of living if he couldn't be with John ever ever ever again?
He wasn't sure.
Sherlock had never needed anyone before. He'd been perfectly happy on his own, solving crimes, irritating Lestrade, doing drugs, smoking, pissing off Mycroft. And then John had stepped in, and it felt like a gaping hole inside him had been filled with that wonderful, incredible man.
(Not that there had really been a hole, of course, that would've been physically wrong)
Well. It was his own fault that he was in this situation. He might as well do some good in the world and spend his last moments helping out MI6 or whomever.
Because they would be his last moments.
He wouldn't live much longer without John, and this mission was going to be deadly anyway.
He'd make sure of it.