If John had known it was going to be the last night he would have with Sherlock, he would have held him a little bit tighter, laid there a little bit longer. He would have spent more time memorizing that smell, that horrible mixture of chemicals and sandalwood. He would have spent more time mapping out the smooth, pale skin beneath his fingers, the tight grip of his lover as Sherlock's hands gripped his own too-tightly.
As it was, John knew something was wrong. He knew it when Sherlock turned to him, clutched the sides of his face and kissed him hard, dry, desperate. Sherlock's thumbs ghosted over John's cheeks and when he spoke, his voice was rich and full and angry.
"Every horrible, tactless, rubbish thing I have ever said to you, John, I meant," his rough voice growled out.
"Oh good," John responded, but Sherlock shushed him.
"Every time I heard your voice crack was you telling me I was wrong, was you dragging me back into his ridiculous, dull, pointless world. I've been horrible to you, and yet you love me still, and I exist here solely because of you. The dull repetition of life would have driven me over a cliff years before, if I had not met you."
John felt panic rise into his cheeks. He wished desperately then to be able to see, just for that second, that split second, so he could see Sherlock's face, so he could know what Sherlock was talking about. Something was wrong.
John shifted, trying to break Sherlock's hold on him, but the curly-haired man held fast. "I don't deserve your love, John."
"No, you don't," John said, speaking quickly for fear that Sherlock might suddenly get up and disappear. "But you have it, and you always will, so remember that. Whatever you're planning, Sherlock, remember that. Please." He begged Sherlock, with that please, to just stay with him.
Sherlock's hands relaxed and eventually fell off, one falling to the center of John's chest, the other coming to rest at his side. "How could I not?"
"What's wrong, Sherlock? Tell me."
"Nothing," Sherlock said quietly.
"Are you ill? Something terminal? Something scary? Cancer, is it? A tumor? Aneurism?"
Sherlock chuckled and shook his head, his curls brushing against the side of John's face. "I'm not ill. Sometimes I forget, John, that you aren't really inside of my head, though for me you are there. For me, you live inside of me and every thing I do, I do with you."
"I'm frightened," John answered honestly, his hands trembling a little. "Please tell me what it is."
"It's nothing, John. I just... I suppose I wanted to let you know... remind you... that I love you. You are my reason for existing John. That's all."
This was unlike Sherlock in every way, and John could only lay there and wonder. He would think on those words later, and the words once spoken by Lestrade, "Sherlock Holmes is a great man, and maybe one day, he might even be a good one."
John would remember those hands on his face, those words rushing through his ears, coursing over him as he lay there at night, alone and the loneliness suffocating him slowly. He would remember that Sherlock loved him as the smell of sandalwood faded into nothing, and Sherlock's side of the bed grew colder.
"You were my reason for existing in this world, too, Sherlock," John whispered to the empty pillow. Sometimes his fingers darted out, hoping against hope, that they would come into contact with Sherlock's warm body. Sometimes, deep in the night, John could still feel him there, feel him breathing, hear his heart beat. He'd wake up alone, but swear that the side of the bed was a little warmer.
Sherlock was gone, and with it John's heart, and the only thing that kept him going most days was that he never gave up hope that there would be that one, last miracle. And as much as he never wanted to live in regret, he wished he had kissed Sherlock that night, just one extra kiss, just in case.