No one seemed to be against it and some people were actively asking for it (myself included :D), so here's some smut. The entire chapter is rated M and nothing relevant to the plot happens, so if you don't like this kind of things, you can just skip it and wait for the next update.

I'm not sure what it says about me that the longest chapter in ages is pretty much all sex ^-

His eyes fly open as soon as he hears a sound behind him, though his quick return to awareness is bereft of the panic that usually comes with it. For one thing, he wasn't really sleeping yet, more like dozing and waiting, and for another, he feels safer than he has in months, so he doesn't feel like jumping up and running at the smallest noise. He suspects he knows who made it.

Sure enough, after a few seconds, two pyjama-clad legs appear in his field of vision, followed by a face as his visitor crouches down next to the couch.

"Hey," she whispers softly.

"Hey."

"Did you really think I'd let you spend the night on the couch?"

"What if I like the couch?" he asks, trying for a serious, innocent tone and failing miserably, if Mattie's expression is any indication.

"Tough," she just says, and gestures for him to follow her.

Smiling at her very Mats-like answer, he kicks the blanket away, gets up as quietly as he can and follows her up the stairs, wincing when one of the steps creaks under his foot. Her shoulders shake a little with repressed laughter and he narrows his eyes at her behind her back but refrains from commenting, knowing it would only make things worse.

At last, they're in her room and she locks the door behind them before turning to him and whispering, "Before you say anything to kill the mood, my parents' room is soundproof and Toby and Soph sleep like the dead. We should be okay as long as we keep quiet."

"You mean while we're sleeping?" he teases.

She takes a few steps towards him and brings her hands up to his shoulders, smiling up at him as his own hands find her waist.

"If you're that tired, sure. But I did promise you a next time, remember?"

"It seems like a lifetime ago, but I remember."

Some of her playfulness vanishes at that and her face turns serious.

"I know a lot of things have happened. If you'd rather..."

"You're the one who's about to kill the mood," he warns before she can go any further.

He knows what she was about to say. She knows that he's not in the most stable place emotionally these days, and she wanted to give him a way out in case he didn't want to add more feelings to the mix. He appreciates her thoughtfulness, but he doesn't need the reminder. And while he is conflicted about where this thing between them is going, unsure whether being a part of his world is really a smart move on her part, one thing he doesn't doubt is the way he feels about her. Plus pretending that everything is fine for however long they have sounds like a wonderful idea.

She seems to get it, because she nods and presses herself closer to him. When she tilts her head up, he takes the cue and leans down to kiss her. As is becoming their habits, it starts out sweet and innocent even though they both know where this is going to lead them tonight.

He feels her sigh in contentment against his mouth, her body all but melting into his, as if she's finally relaxing after days spent on her guard. She's been so supportive and just there since he came back – and before that – that he tends to forget that it can't be easy for her either, shouldering his and his family's problems as if they're her own, helping him through it, unsure if or when he's going to crack.

The thought of everything she's done, everything she is, has him tightening his hold on her, and while it was just supposed to be a way to show his gratitude, it quickly turns into something more when her hands leave his shoulders, one going to his neck to bring him closer, the other sliding down his side and underneath his t-shirt to rest against his skin just below the bandage. Her fingers are warm and he hums in appreciation at the light caress, making her smile into the kiss. He takes advantage and nibbles at her lower lip, asking for a permission she's more than happy to grant.

The kiss deepens and he feels his pulse quickening in anticipation as well as other parts of his anatomy reacting.

When she feels the effect she is having on him, Mattie breaks their embrace and gives him a shy smile as she takes a step back and takes off her jumper. What she's wearing underneath comes as a surprise. He's so used to seeing her in loose clothes that the formfitting tank top seems odd for a second, but the challenging look she's giving him, letting him know that it's his turn, quickly distracts him from his observation. Part of it is for show, he's pretty sure she's not as confident as she's trying to seem, but then, neither is he.

It's been a while.

"Did I mention how nice it is to see you looking like yourself?" he asks, his fingers playing with a strand of her hair.

She raises her eyes to meet his and smirks.

"Knew you didn't like my synth look."

"Guilty," he acknowledges.

Not so much because of what she looked like with straight hair and bright green eyes – though it was disconcerting – but because of what it meant. That she had to keep up the act because she was in danger. He's been busy dealing with his father's return from the dead, but it doesn't mean he didn't take a minute to notice that she got rid of the disguise sometime between when he went with Hobb and when Niska brought him back to the Hawkins'. The significance wasn't lost on him – she's safe.

Plus, yes, he has to admit he likes the wavy hair better. It's more her.

"And you're just staring at me because…?" she says, curious about his change of mood.

He shakes his head to get rid of the thoughts there and focus back on the present.

"Sorry."

"Do I need to activate the adult mode?" she jokes.

He has to laugh at that.

"I thought you already had."

"You haven't seen anything yet," she promises, getting closer to him once again and helping him get rid of his t-shirt.

Once he's half-naked before her, she lets her fingers brush against the bandage around his upper body and locks eyes with him again.

"Do you want to take this off?"

He's so taken aback that he doesn't know what to say at first and he stammers a little.

"I… It's… not pretty," he ends up settling on.

She's seen it before, but it was different. He was either unconscious and in danger of dying, or taking care not to completely uncover the wound.

She gives him a blasé look.

"Seriously? What do you think I'm going to do? Run off?"

"No, but…"

Seeing that he's having a hard time with this, she places a quick kiss on his mouth before leaning back, one hand still at the edge of the bandage, the other resting against his cheek to make sure he's looking at her.

"You can leave it on if you don't feel comfortable taking it off. But I'd like to be able to touch as much of you as I can."

She will never stop surprising me is his last coherent thought.

He can't reply with words, so he surges forward and captures her mouth again, his movements so quick that she loses her balance a little and takes a step back to restore it, but he's right there with her, holding her against him while managing to push her back until she's pressed against the door, and she moans in a mix of pleasure and surprise, but it doesn't take her long to catch up and suddenly she's kissing him back with everything she's got, and he's lost.

In fact, he's so preoccupied with her lips that he doesn't realize her hands are inching towards the dressing again, and only when she breaks the kiss to look at him, glance at his side, and then look at him again does it occur to him that she's asking for his permission. He just nods, past caring as long as she keeps kissing him, and she gives him a blinding smile that makes it worth it as she carefully starts unrolling the bandage until his torso is completely bare and she places the gauze on top of her dresser. She doesn't even take the slightest look that could make him uneasy, but as promised, her hands immediately start wandering over his chest, only avoiding the part where she fears it might hurt him. She steals another searing kiss and he forgets all about feeling self-conscious about the gaping hole in his side.

It's now his turn to slide a hand under her top, his fingers brushing the underside of her breasts in a teasing caress that has her rubbing against him in reaction. They break apart just long enough for her to raise her arms and him to lift her top over her head and let it fall to the ground, and then they're back in each other's arms, naked skin finally meeting. He avoids her searching mouth and he attaches his lips to her throat instead. He sucks lightly at first, then a little harder, and her head falls back against the door as her nails dig into his skin at the small of his back and a string of profanities falls from her mouth.

"Shh," he murmurs against her skin without stopping his ministrations.

"Shit," she utters, her voice much lower now. "Forgot." He raises his head to say something, but she glares at him. "Don't stop."

He nearly chuckles at her matter-of-fact command, but he manages to hold it back though his eyes are shining with mirth. She retaliates by narrowing her eyes at him and bringing a hand up to his neck again to pull him back to her throat.

And he'd like to make a joke about her impatience, except her hands are now traveling lower and following the outline of his erection through his pants and he's not faring any better. His hips give a little jerk forward, trying to increase the pressure, and he can feel her victorious smile when he kisses her mouth again.

Then she pushes him back and motions at something behind him. He doesn't need to look to know what she's showing him. Taking her hand in his, he starts leading her towards the bed, but she shakes her head.

"Give me a second."

He raises his eyebrows but leaves her to it and goes to lie down on her bed, watching her as she rummages through one of her drawers. She turns to him, triumphantly raising a hand holding a box of condoms.

He's glad she thought of it, because he's not sure he would have.

She skips to him, her half naked state apparently forgotten as she focuses on opening the box. He sits up and sneakily slips his arms around her, making her fall on him, and she all but shrieks before bringing a hand to her mouth to silence herself. Sitting in the space between his legs, her own thrown to the side over one of his, her arms around his shoulders to steady herself, she buries her head in the crook of his neck to try and muffle her laughter, and he takes advantage of the position by attacking the side of her throat he neglected earlier. Sighs of pleasure soon mix with her giggles, and this might be the most beautiful thing he's ever heard.

She adjusts their position so that she's straddling him and their hips instinctively find a rhythm, moving together, the friction nearly driving them mad even though they're still mostly dressed. Her hands come up to frame his face and bring his lips to hers before sliding into his hair, her nails raking lightly against his skull. The strangled sound of approval this drags out of him is swallowed by their kiss but she hears it and does it again, on purpose this time.

At some point they can't take it anymore, and he lifts his hips so that he can slide his pants and underwear down, but she needs to scramble away to get rid of hers. There's some fumbling and stifled cursing, but at last, they're both naked, and he would like to take a minute to look at her, but she's already back on him, pushing him back and licking her way down his chest with a clear destination in mind.

As much as he would love to feel her mouth on him, he has more urgent priorities right now, so he stops her before she can really get anywhere and motions for her to come back up.

"Maybe next time," he just says in answer to her confused look, fishing a condom out of the box she left on the bed and tearing the package open.

"So you think there will be a next time. Leo Elster, are you becoming an optimist?" she asks in mock shock as he rolls the condom over his length.

He shoots her a look that is part annoyed, part amused. He shouldn't be surprised that they can go from frantically undressing and trying to devour each other to bantering in the blink of an eye without losing any of the passion that has been brewing between them since she locked her door. They've always been quick at reacting to each other's moods and they're both too smart and observant to miss it if something funny or out-of-place happens in any given situation, why should this be any different?

"There might be. If you play your cards right," he shoots back.

He can see her swallowing back the urge to laugh out loud at that and he smiles.

"I'll do my best," she says.

He thinks he can detect a hint of uncertainty beneath the playful tone and he gets it.

This is clearly not her first time. It's not his either. They both know they've got this. They're certainly willing and ready enough, if his hardness and her dilated pupils and laboured breathing are any indication. There is no reason for them to be anxious. Still, there is something slightly nerve-wracking about tonight and he thinks he knows what it is.

No one has ever accused him of being a hopeless romantic, yet he can't help but note that feeling the way he does about her makes this noticeably more meaningful than his past experiences, and he'd be willing to bet that the same goes for her.

It's not the physical aspect that gives them pause. But those emotions are turning this into uncharted territory.

"You're staring at me again," she reproaches.

"Sorry. It's just…"

When he trails off, she softens.

"Sort of weird and overwhelming, right?"

He chuckles, and there's relief that they're on the same page in the sound. It's a very Mattie way to put it, he couldn't have said it better.

"Yes."

"Still, don't kill the mood now, or I'm gonna have to strangle you," she swears, straddling him again and throwing him a pointed look.

"I'll do my best," he echoes, chuckling again.

He sits up so that they're at eye-level and wraps an arm around her middle. She smiles approvingly and guides him with her hand, never breaking eye-contact. Once he's fully encased in her heat, she closes her eyes and pauses for a moment, giving her body some time to adjust.

"You alright?" he asks, fighting to control the urge to move.

"Better than that," she answers, and there is none of the self-doubt and uncertainty left in her voice, only a pleasant breathlessness and promises of bliss.

She starts rocking above him and his breath catches in his throat, his arm tightening around her. The pace she sets is unhurried, her movements deep and languid, just forceful enough to slowly heighten the sensations but not so much that he feels frenzied and doesn't get to savour the moment.

"Perfect," he mutters into her hair before lowering his head and peppering kisses along her shoulder, down her collarbone and the top of her breast.

She leans back a little to give him better access, never breaking her rhythm, and he captures a nipple in his mouth, teasing it with his tongue. She lets out a low hum, one of her hands burying itself in his hair, keeping him in place, while the other one moves to stroke any part of him that she can reach, seeking as much skin contact as possible.

His hand travels to her neglected breast, caressing and squeezing lightly.

He's not sure how long it lasts – doesn't want to know, to be honest, would rather keep this moment timeless – but eventually the pleasure starts building to a point where neither of them is satisfied with slow and aimless anymore and he begins thrusting up as she purposely quickens her pace, the change drawing matching moans out of them.

She guides his head back up to hers, and their kiss gets more frantic with each thrust, echoing their bodies' loss of control. He can feel her tensing even as his own release is getting dangerously close, and she holds him harder and digs her nails into his shoulders, and suddenly she's shuddering against him, a small whimper escaping her in the midst of her climax when she feels him letting go as well. He lets his forehead rest against her shoulder as the wave takes him.

The next thing he's aware of is her hand stroking his hair, and he raises his head to see her face, finding her looking at him with a lazy smile.

They just stare at each other for a few seconds, unsure what to say, how to put what they just shared into words – unsure if they can or should. Then he sees her eyes light up with humour and he knows what is coming.

"Aren't you glad you didn't stay on the couch?"

He shakes his head in amusement.

"Definitely."

She gives him a quick kiss before standing up. He should have guessed she wasn't one to bask in the afterglow for very long.

"I'm just gonna clean up a bit, I'll be right back. There's a bin under the desk."

She gathers a few things on her way to the bathroom and he just stays where he is a bit longer, recovering. Then he gets up to take care of the condom and put his underwear, pants, and bandage back on. He can't find his t-shirt, and he's still looking for it when she reappears. Wearing it in place of her pyjama top. Figures.

"Now that's a look I could get used to," he comments.

"Right back at ya," she replies with a leer at his mostly naked chest.

He watches her as she walks over to the bed but he stays standing in the middle of the room, uncertain. He was just thinking about going back to the living room, but she locked the door again as soon as she came back, presumably to make sure no one will disturb them in the morning, which seems to imply that she means for him to stay.

"Hey, look," she says, crouching down next to the bed and holding up the cord he left there when he woke up earlier. "Do you need to charge?"

One day, he'll get used to how practical and straightforward she is about his synth parts, not a hint of reluctance or hesitation in the way she just goes with it, but today is not that day.

"No, I'm good."

"Sleep, then," she says, lying down and patting the spot beside her in invitation.

"Shouldn't I go back to the couch?" he asks as he sits down on the bed, thinking about how this will look to the others tomorrow – an empty living room and a locked bedroom door.

"Depends. Do you want to?"

It occurs to him that she may think that he doesn't want to spend the night with her. The sudden flash of insecurity is hard to reconcile with her character – not to mention absurd given just how much he does want to stay – but he guesses that some awkwardness is to be expected.

"No."

She smiles in obvious relief.

"Are you worried about your family's reaction?"

He almost snorts at that. They couldn't make it any clearer that they approve of Mattie – well, except for his father, but he doesn't get a say – and they're not exactly coy about sex. Plus they probably think that their first time together occurred a while ago anyway.

"Not mine. Yours."

"My mum wasn't fooled for a second and Dad will just have to deal with it."

He gives in and lies down next to her, facing her. Still a bit hesitant, he brings his hand up to her face to brush a strand of hair behind her ear.

"Are you sure it's…"

"Leo. Sleep."

So he does.

TBC…