A/N: I have no idea where this came from, to be honest. I just liked the idea and then it went off in it's own weird direction. Probably has far too many layers for such a short piece, but here we are. Inspired by listening to the "Taken By Trees" cover of Sweet Child O Mine five thousand times on repeat.

He's finally realized that the reason he couldn't sleep for six years was that he never adapted to not having Mac sleeping next to him. So when Will wakes up without any apparent cause, all he has to do is grope the sheets and, eyes still closed, find her no longer in bed. And since he's not going to fall back asleep until she's asleep, he sits up and, in the middle of a bleary questioning look at the bathroom, hears music coming from the living room.

It sounds like, but it couldn't be—

Shuffling out of the bedroom, he sees Mac sitting on the couch in her underwear and his discarded tee-shirt, hair piled high on her head, with the Gibson J-15 across her lap. She's holding it somewhat uncomfortably—not because, Will thinks, she doesn't know how to hold a guitar but because she isn't sure if she should be holding this guitar.

Stiltedly, as if they don't quite remember how, her fingers pluck out the chorus to Sweet Child O Mine until she's able to play it at something resembling tempo.

"When did you learn to play?"

"Sorry," she startles.

He can't tell if she's apologizing for touching one of his guitars without permission—despite his repeated insistences to make herself at home over the past month, MacKenzie has only somewhat availed herself of his apartment, and he knows that she's probably not unafraid that he's going to ask for the ring back when Jerry's lawyers respond to their response to the suit—or for waking him up.

"No, I didn't know you could—"

Her mother would hire Mac tutors in every city that her father's position dictated that they lived in, but Mac was never moved to dwell too long on any particular instrument, even if she became more than proficient at reading music.

"Jim taught me." And then, after biting her lip, "Only a little. I couldn't sleep and it was too late to take a Benadryl, or something. Sorry if I—"

"Overseas?" he asks, because they're still navigating her twenty-six months as an embed and the nearly-three-years gone, and he's realizing in piecemeal how much he doesn't know about this fiancée of his. "Jim taught you while you were overseas, I mean."

Humming, her eyes escape his and look down at the frets as she nervously plays the next few bars. "During our time in Peshawar, a Humvee we were in drove over an incendiary device. Somehow didn't flip, but the glass shattered." She stops playing, but the fingers on her left hand continue pressing down on the strings. "Jim's palms were shredded—they looked like raw hamburger. But we still needed to do something to pass the time, so he taught me the tabs of a few different things until his hands were healed enough that he could play again. I'm surprised at how much I remember."

Were it a different time of day—not four in the morning, perhaps—that wouldn't have been the answer he was expecting. But it's too late, too early, for any expectations at all. Will thinks that it might be a running theme at this point of this year, at the grey beginnings of December. Mac's belligerent acquisition of guilt has given way to something softer that bends under his touch. But he doesn't want her to yield, either.

"What did he teach you?"

Mac scrunches up her nose, before leaning back against the couch cushions and resting the guitar against the flat of her belly. "It was… Somewhere Over the Rainbow, and then Landslide. And um… Hallelujah. We never had the time for me to actually learn… how to really play. Notes and chords and everything. Jim lost his last pick like three months in, so I mean…"

Idly, he reaches up a hand to check if the strings are in tune. They are. Close enough, anyway, and wonders if Mac did that too. "When was the last time you picked up a guitar?"

"Years," she says with a dry little laugh. "It was something we did. And then Jim and I stopped spending twenty-four hours a day together, and… I was only learning because he was my teacher. That sounds dumb. I don't know. He was so eager to teach me something, and he had the cutest little crush on me back then…"

She smiles.

"Can't say I blame him," he finds himself saying, gently dropping a hand on top of her bare thigh.

What was she like, back then? he asked Jim, not too long ago. Uncomfortable, Jim had shrugged, loosened the knot on his tie, and answered: Sad. Very kind, but also very sad. We all wanted to make her happy, but none of us knew how. The words So if you make her sad again, I swear… hung between them like an unplayed coda.

Rolling her eyes, she attempts the opening to With Or Without You before stopping as quickly as she's started, her hands running out of muscle memory to keep going.

"He made me learn Stacy's Mom, too," MacKenzie snorts. "Ask him about that, if you ever want to make him stammer. That, and penguins."

"Like the hockey team?"

"No, like the bird," she says quietly, her face dimming again.

The curve of her body unfolds into the lines of the couch. In the low light, her face is reduced to shadows—Mac only bothered to turn on one of the floor lamps. His thumb traces circles into in the inside of her knee, and slowly, she looks at him again like a question.

Will doesn't think he has any answers for her. For so long he's been telling her one thing and doing another. All he can do now is lean in closer, wrap his arm around her shoulders, keep his other hand on her knee. Mac lets out an exhausted sigh, tilting her head to lay against the back of the couch. He may have promised to never hurt her again, but it'd be unfair of him to expect her to break the habit of anticipating punishment so quickly.

Lightly, he kisses the hinge of her jaw, lingering there for a few seconds before resting his lips against her temple for a long moment. "What woke you up?"

"I had a nightmare. Can't remember for the life of me what it was about, though." She shrugs, and he wonders how silently Mac's learned to be afraid. Will prefers it when she's belligerent, although he would never fault her this terse disquiet. "I almost called Jim, which is… stupid. And then I came out here and… his guitar was a piece of shit. Not like…"

She means that his is waxed and well cared-for. But he remembers the first guitar he ever bought at a thrift store when he was fifteen, it's chipped finish and weak truss rod. Dance and Broadway was verboten in his father's house, but a guitar, at least, tread closer to John McAvoy's prescriptive masculinity.

MacKenzie laughs, trailing her fingertips down the gleaming maple backing on the neck of the Gibson. "I mean, it got toted across three different countries and was bombed and shelled at least seven distinct times. He played for me a lot. It reminded me of you."

Breathing deeply (his nose is pressed against her hair, and she smells like lavender and juniper, because he's managed to convince her to at least leave shampoo and conditioner here, and it's a start) he kisses her again.

"You could have woken me up."

Giggling she angles her face towards his; his mouth can reach her cheekbone. "For what it's worth, I do know that."

"Then why didn't you?" She shifts her face again, and he kisses an eyelid.

"What would you have done except sit up with me?"

Again she turns her head. A game now, he kisses the tip of her nose.

"MacKenzie, I'm kind of sitting up with you anyway," he points out, the corners of his mouth lifting in what is probably a weary smile. "I don't sleep well when you're not there, which may or may not mean I've been a sleep-deprived jackass for years. So you might as well just kick me until I'm not asleep anymore or something."

She sighs sweetly.

"Billy."

Sliding his hand up her leg—she's getting cold, he thinks—he places his fingers over hers where they're resting on strings. "Do you want me to teach you? How to actually play?"

Will's never actually taught anyone how—one of his younger sisters asked him to, decades ago, but she was ten at the time and not overly-committed to it—but he likes the idea of Mac curled up on his lap, their hands tangled together over the fretboard as he shows her notes and chords and scales.

That garners another real smile from her. "Yes. Although probably not right now. We have the rest of the weekend."

"We have the rest of our lives," he murmurs.

Making what he thinks is a pleased sound (breathy and lopsided, from high in her chest; when he hears it in his ear during a broadcast he knows he's done something right) she kisses him, a light touch of her lips against his.

"I could stand to go back to bed now," she whispers.

Unwrapping himself from around her, he takes the Gibson off her lap and stands, walks over to the line of stands near the windows, and puts it back into its place. When he turns back around to face the couch, Mac is an enervated mass of limbs against the leather. He offers her his hand, and gently pulls her to her feet. Rubbing her eyes, she smiles, and doesn't let go of his hand—so he leads her to bed, climbing in after her, pressing his face into the back of her bare neck and draping an arm over the dip of her waist.

"I'm serious," he reminds her, disliking how urgent his voice sounds. He kisses the back of her neck, compensating somehow. "Wake me up, Mac."

Exhaling, she nods, and then turns in his arms to press her face against his collarbone. And then tangles their legs together next, curls an arm around him, digs her fingers into his tee shirt.

It feels like a beginning.

Thanks for reading!