"What?" he mumbles, forgetting for a moment, until Harry reappears at his elbow.
"Oh. Right." He sighs in defeat, the fury draining away as resignation takes its place. These things would happen and he would be unable to stop them. He swallows. "Why are we here?"
She lifts a finger, and John follows it to where a man is sitting on the railing over the churning, freezing waters below.
"God. No, god, Harry," he says, and breaks into a run against the viciously whipping wind. He reaches Sherlock, who has not moved in the three seconds it took John to make it to his side. He still does not move when John's hands pass uselessly through him in his vain attempts to pull him back from the rail.
"Sherlock," he moans, terror and defeat coalescing in the pit of his stomach, turning it as cold and choppy as the river.
"I'm sorry, John," Sherlock says, and John nearly jumps out of his skin in surprise - until he realizes Sherlock is speaking into the empty air of the city.
"For what?" he replies anyway, his face softening as he looks at the detective. "You're not going to do it. No. You're not."
"It's just… been difficult, to do things anymore. Without you. And the world is difficult to handle without you. You made it easy, John," he sighs wistfully. "You made it less… noisy, in my head. And I became used to that feeling, so when you were gone…"
"I'm not gone, I'm here, I'm right here," he whispers, his hands passing frantically through Sherlock's body like smoke.
"It was like an addiction, and the withdrawal has been more painful than I was expecting." His eyes slam shut. "I didn't see this coming. I should have noticed the signs. I should have seen it and done something, not let you suffer alone. I just didn't know how to help you. You were dying, anyone could see that. But I just didn't imagine it would be you to hurt yourself. And I never imagined you'd be the one to hurt me, too."
"I didn't mean to, I swear, I - I wasn't thinking," John cries, eyes growing hot as he watches Sherlock stand unsteadily on the edge.
"I'm sorry I was so awful to be around that you had to… do what you did. But, never fear, I won't make the same mistake twice. The world is better off without me, John. I just wish that. I just. I wish you could have known that you made my world a better place," he says awkwardly, his confession strange to his own ears.
John feels the sobs shake his shoulders; the hot paths of tears that scorch his face. "You made mine better, too. I never wanted to hurt you. I was selfish and hopeless and stupid and please, Sherlock, no, no. None of it was your fault. This world needs you; needs the light in your eyes when you find something out, needs your intelligence and your quirks alike, needs the stupid way in which you never pick up the goddamn milk, needs you, everything about you," he shouts. "And I'm sorry for not seeing that I was needed, too. I'm sorry for everything."
He buries his face in his arms, because he doesn't think he can stomach the sight of Sherlock throwing himself away. He rocks back and forth, mourning for the life he wasted and the consequences he never imagined. Looking back, it seems so foolish, so brashly pessimistic. How could he have not understood it before?
"Please, I'm sorry, I'm sorry," he murmurs through the tears. "Take it back. I take it all back. It was bad, yeah, but… I'm sorry for not remembering that it gets better. And, and it was already good. I had a good life. I was… I was needed. And sometimes that's all you need. To be needed. I'm sorry for not seeing that. Letting the bad stuff get to me. Just… let Sherlock live again. Let him be okay. Please, God, please…"
He has no idea how long he sits on the cold ground, praying, crying, before a voice carries him back to reality.
No. It can't. It is…?
John lifts his stained face to see Sherlock standing uncertainly a few feet away.
It is night, it is snowing, and Sherlock is alive.
John leaps to his feet, staggers forward, and stares openly and wondrously into Sherlock's confused face. "Sherlock," he breathes. He cannot quite believe it, but it's true. This is his second chance.
"I deduced where you'd be, it was quite simple, really. I came to see if -" He is cut off by John's entire body slamming forward and crushing him in an embrace, and the pressure of warm lips against his own. He makes a startled noise, but John feels his mouth curve into a smile.
When John pulls away, there's an amused edge to Sherlock's concern. "Are you alright? I know, back at the flat, and the past few months…" he trails off, unsure, undisguised worry creasing between his eyebrows.
John smiles, looks up at the sky. Thank you. You did it, Harry. You saved me. He wonders if Harry got this chance, and then decides that no, probably not, and either way, she chose to move on. He wishes, not for the first time, that she were still here - there's so much more he needs to tell her, so much more he has to apologize for, so much more he has to fix. But, looking into Sherlock's questioning face, he supposes everything happens for a reason, and he's thankful she was there to show him the way. They got their second chance, too. He wonders if she's proud of him and the choice he made. He hopes that even after everything, she still is.
His hand finds that of Sherlock, who flushes through a dazzling array of surprise, embarrassment, and pleasure. "I will be," John says, and leans up for another kiss.
For the first time, he believes it.
"What happened to you?" Sherlock asks, bewildered but clearly pleased.
John's face grows serious. "I realized some things. That there are good and bad times, but all in all, we have a good life, Sherlock. A very good one. And I at least have you to thank for that. Don't you… don't ever doubt that you are the best thing to happen to me. You, you mental, strange, brilliant, fascinating man. I don't ever want to be in a world without you in it. You make my world a better place," he says simply, almost shyly, but the words are true and right.
This time, it is Sherlock who tilts his head up and kisses him.
"Happy Christmas, Sherlock."
"Happy Christmas, John."
And it was a happy Christmas indeed.