Sherlock was bigger than Mary had imagined. She gasped out loud when he dropped his trousers and pants, but John's grunt of approval drowned out her own soft exclamation.
John, already naked and sitting back against the headboard of Sherlock's bed, licked his lips and began to stroke himself. "Hope you're not fussy about who tops and who bottoms," he said, and after a few more quick pulls, went to his hands and knees, turning on the mattress to present himself to Sherlock. Mary hoped he knew what he was asking for. He had certainly had things up his arse before, but the silicone strap-ons she had used to peg him weren't in the same class as Sherlock's fully erect penis.
"Sherlock, do you even have lube?" Mary turned where she stood near the bed, glancing around the room as she tried to guess where he might keep it, but Sherlock had already darted toward his nightstand. He rummaged through a drawer that appeared to hold mostly discarded electronics—old cameras, an iPod with a shattered screen, at least three mobile phones—before coming up with a slim tube that had been buried beneath everything else. Clearly, he hadn't had sex in a while, but she knew what else he'd been up to lately. She didn't think it was likely that he'd be fucking her tonight—maybe someday, but not this first time—but for John's sake she should ask about condoms. She opened her mouth and then stopped, remembering that she was trying not to doubt him anymore, and while he'd certainly risk himself she didn't think he'd ever knowingly endanger John.
Sherlock flicked open the tube of lubricant, dislodging the dried-up ring around the cap. John dropped to his stomach, legs spread so he took up nearly all the available space on the double mattress. He raised his arse and made an impatient noise and Sherlock climbed onto the bed to straddle him, moving with more care and deliberation than John had. He tipped the tube to squeeze some of its slick contents onto his hand. "If I'd known how eager you were—"
"You've known forever," John said. "I don't know why you never did anything about it."
Sherlock paused, the hand that wasn't full of lube splayed across John's left cheek, his thumb stroking gently at the top of his cleft. "I didn't think I'd be good for you."
John laughed, brittle and dark. "You're not. We're terrible for one another. Always have been. But we're all we've got, so I guess we have to make do, hmm?" He bucked his hips, raising himself toward Sherlock again.
"Oh, John." Mary took a step closer to the bed. "We've all done terrible things to each other, but we don't have to keep doing them. That's why we're here, isn't it? To make things right, to make them how they should have been from the beginning." She tried to sit down on the edge of the mattress next to him, but there wasn't enough room, and he didn't move over like she expected him to. In fact, he turned his head away, tossing the pillow to the floor so he could look straight ahead.
"Come on," he said to Sherlock. "And don't bother starting with your fingers. The only thing I want inside of me is your cock."
"Sherlock," Mary said, warning, but he ignored her. She couldn't really blame him, given that he had John's willing arse practically waving in his face. He did as John requested, thoroughly spreading the lube over himself before lining up to push in slowly, pausing with each groan he elicited.
Mary had assumed she'd be in bed with them by this point, but watching held almost as much appeal, and it allowed her to notice the details she might have missed if she were more involved. Now she could see that Sherlock's arms and legs were trembling slightly as he held his weight over John's back, though his voice was admirably steady. "Are you sure this is okay?"
"God, yes, can't you tell? I thought you could deduce anything." John thrust back against Sherlock, hips rising from the mattress, and Mary caught a glimpse of his erection, dark and wet-tipped, bobbing against the sheet beneath him. She wanted to wriggle her way under him, to impale herself on that cock she knew so well, and watch his face as Sherlock pounded into him from behind, but she thought maybe this time she should leave them to work it out with each other first.
She stepped back from the bed again, wrapping her arms around herself. She was naked, but she didn't remember undressing. She didn't see her clothes—they must be on the other side of the bed. She had stood over there when they'd first come into the room, hadn't she? The three of them, all together, John and Sherlock stumbling in first, her following behind them. Of course she'd followed them—what else was she supposed to do? This whole thing had been her idea, hadn't it? A long time ago. A lifetime ago, really. Back when Sherlock had first returned from the dead, which was a pretty neat trick, now that she thought about it. At the time, John had flat-out refused her suggestion that the three of them might try being more than just friends, insisting that Sherlock would never be interested. But now they were finally here, and maybe her little fantasy where they all lived happily ever after wasn't gone forever. Maybe this could still work. If only—
A moan from John that was unmistakably one of pain made her lose her train of thought.
"Sorry, sorry," Sherlock gasped, and lifted some of his weight off John, exposing an inch or so of the base of his cock.
"No, it's okay," John said, voice rougher than Mary had ever heard it in the bedroom. "Keep going. I want to feel it. I want it to hurt."
"John." Sherlock pulled away, cock slipping out, to sit back on his haunches behind John.
"Please," John said, twisting his neck to look over his shoulder at Sherlock. "Please. Do this for me. I've hurt you enough. I want you to hurt me."
"No." Sherlock ran a hand through his hair and then shook his head. "This isn't about revenge. I thought we both wanted to—"
"Yes! We do, I do. But, please. Fuck me so hard I can still feel it tonight when I take Rosie home and go to bed without you."
"No. Do it. Just this time. We can do it again, another day, different. You want to, don't you? Us, I mean."
"I...." Sherlock trailed off. "I'm not really sure what you mean." He put a hand over his own softening cock, gave it a slight tug.
John rolled over onto his back. "What I mean is. After years of—not being together. We can be. Together. Like this. All the time. Is that what you want?"
"Yes. God, yes, John. That's what I want."
"Good. Me, too. And later on we can try all sorts of things to figure out what we like best. But right now, today, I need you to do exactly what I tell you to do. Take me. Hard."
"John." Sherlock still didn't sound quite convinced, though his cock was thick beneath his fingers again.
John sat up, pulling his legs in so he could lean close to Sherlock. "Sherlock Holmes, for once in your life, listen to me. I am going to turn around and spread my legs again, and you're going to take that ridiculously large prick of yours and ram it so far into my arse that neither one of us can breathe." His voice got lower as he spoke, so Mary had to strain to hear. Sherlock sat frozen, eyes unblinking, every ounce of his attention clearly focused on John as he continued. "Then you're going to fuck me as hard as you can, fast or slow, your choice, but you're not going to stop until both of us have come. Do you understand me?"
"Yes—yes. I understand." Sherlock was up on his knees again in the blink of an eye, hand on John's hip to help turn him around more quickly. Watching, Mary stumbled back until her knees hit the chair in the corner. She dropped into it, not even feeling the scratch of the ancient upholstery against her bare skin.
Sherlock picked up where he'd left off, though this time John stayed upright on his knees, as well. Sherlock was flexible enough to neutralize the height difference. They didn't last long. John guided one of Sherlock's hands from his hip to his cock, showed him how he preferred to be touched, rough and fast—Mary knew he liked it like that even when he wasn't begging for pain. And John did beg, alternating Sherlock's name with pleas to be taken harder and deeper, which Sherlock obeyed, until their movements together began to grow more and more erratic. "Now! Now!" John demanded, and reached up and back to wrap his fingers in Sherlock's sweat-slickened curls. Sherlock bent his neck, bringing his open mouth down to John's shoulder, and John cried out as Sherlock sank his teeth into the sensitive skin.
From her spot in the corner, Mary could just see the tip of John's cock as it twitched and spurted, soiling the sheets of Sherlock's bed with years' worth of pent-up desire. She still couldn't see his face, though, just Sherlock's back as he curled around John's body, panting and shuddering his way through his own climax.
Mary found she couldn't move from where she sat, so she stayed where she was, transfixed, jealous and pleased and frightened all at the same time. She hadn't even touched herself yet, and they were already done. She settled one hand between her legs but kept it still, waiting.
After a few long seconds Sherlock pulled away from John, earning more gasps from both of them. They collapsed next to each other on the bed, which really was just big enough for the two of them.
"John." Sherlock's breathlessness sounded more like amazement than exhaustion. "I didn't think I would like that—I really don't want to hurt you—but, God. That was fantastic."
John chuckled, then winced as he shifted and rolled onto his side to face Sherlock. "We don't always need to be that rough, but I'm not surprised you liked it. I'm good at knowing what people like, you know." He ran a finger up Sherlock's arm, making him shiver. "I could always tell what Mary wanted, even if I didn't always give it to her."
"You could," Mary said. "You can." She knew he still felt guilty for texting another woman while she was stuck caring for a newborn, but she'd never doubted his love. She lifted her hand from her lap and wiped at her eyes—this was no good. John and Sherlock had finally, finally fucked in front of her and she was crying instead of joining in like she'd always imagined.
Sherlock frowned and put his hand atop John's on his own arm. "I still don't understand why you wanted me to hurt you, if that's not something you always like."
"I—I don't know. I just needed it, this time. To—I don't know. To know it was real, I think."
To know it was real. Yes. That was what Mary wanted, too. And it was real, what she'd just seen between the two of them. The natural synchronicity that enabled them to time their climaxes together even their first time, the spilt semen from them both in which John was now lying, the way they were touching each other with more tenderness than anyone else who knew them would ever have suspected. All real. But that was it, wasn't it? Just the two of them. She wasn't in the bed with them, not between them or even shunted to the side. And she wouldn't be. She wouldn't feel John's cock again or know what it was like to touch Sherlock's hair when it was coated in sweat and sticking up at all angles like it was right now.
Because she wasn't real, not anymore. She talked to John and Sherlock and sometimes they each talked to her, as well, but they never heard her, not really, because she wasn't here. She started to blink her eyes closed in frustration, then remembered that when she opened them again she might find herself someplace else. She had no control over where she went, now that she was dead. And she didn't want to miss this, didn't want to leave now that John and Sherlock were finally, finally giving each other what they wanted and needed and deserved from each other. She wanted to stay and watch for as long as she could, even though she knew her time wouldn't last, knew that soon she'd be gone, knew that no matter how much she wanted it, there was no longer enough room in this world for her, to say nothing of any room in the bed with her loves.