He does enroll, as Doctor John Song. In a doctorate of archaeology program, with almost all his required credits waved due to documentation of a handful of his previous doctoral degrees (with the dates fudged, of course). The only class he wants to take is River's.

River rolls her eyes and calls him a nostalgic idiot.

The students call him Doctor Song.

He laughs and gently corrects them. "No, no. Doctor Song is my wife - just call me the Doctor!"

He stays as long as he dares - for her entire course, for the entire semester, for the entire year. Slotting in guest lectureships in various departments when River absolutely threatens his bodily integrity unless he lets her get some work done.

...

At first, he is afraid to go near the TARDIS. Their time together has the heavy, still weight of being stolen, and he's terrified that if he steps foot in the TARDIS time will rush forward again and carry him away (from her).

He drags River out to every corner of the Lunar colony. When he runs out of new bits of Luna to explore, they even take the space-port hop back to New Earth. He convinces her it's for the novelty. "Come on, River - you can't tell me you've never been?!"

River rolls her eyes as she takes a window seat and tugs him down next to her and thankfully out of the way of some commuters that look spectacularly nonplussed by their upcoming trip. Teleports are faster, but the private ones are expensive and the public ones are sparsely dispersed. "I have a vortex manipulator, sweetie. Never really saw the point in taking the scenic route."

"Well, there's a first time for everything, River Song!" He bops her nose and looks around for the tea trolley. There's always a tea trolley on these things.

River catches him before he can unbuckle his seatbelt and jump into the aisle, doesn't openly laugh at him while he has a lengthy conversation with the automated trolley robot regarding tea choices, and rescues his tea from the little pull-out tray when his knees bump it and nearly send it flying. He's never been more in love with her, even as she huffs at him and mutters under her breath, "It would certainly be a first if you could sit still for five seconds, Doctor!"

He spends most of the trip crowding River into the window, with the excuse of trying to see out. He really is trying to see out the first few times, but there's hardly all that much to see in this quick corner of the Milky Way 4.0. There is, however, something to be said for a reason to press in close to his wife. The little smile that tugs at the corner of River's lips says she's figured him out. The Doctor just grins and leans closer, pointing out all the colonized stars they can see as they whiz past, looping around several outer planets in the solar system to avoid traffic before eventually making their way into New Earth's atmosphere.

He insists that they take the full route, all fifty-seven planetary stops, and River looks at him like he's lost the plot. "Scenic route," he reminds her, unable to stop from bouncing slightly in his seat as the people rush past them to exit or enter at each stop.

River shakes her head. "Have you ever actually been on a commuter flight for fifty-seven hops, sweetie?"

"No. That's the point, River!" The seatbelt rules are quite ridiculous, and his hand brushes River's thigh as he fiddles with the mechanism. She inhales softly at the touch but doesn't chastise him, so he does it again, purposefully.

River's eyes dart between his face and his hand before she nods shakily. "All right. I'll try to keep them from throwing you off, Doctor."

"Oh River," he presses her closer into the window, "what would be the fun in that?"

They manage a perfectly respectable twenty stops and end up unceremoniously tossed off in some nearly abandoned desert outpost.

...

River tries to coax him out of the solar system, but he digs in his heels. He tells her he's studying, or makes plans for them to go to museums or to Dean Chalmer's. He throws her an elaborate party for every single current holiday - her birthday and his and their anniversary and Christmas - in order.

When all else fails, he tumbles her into bed and distracts her.

Later, he tells her softly that he wants to do this right - just them, just this once, all in one place and time. River stares at him for a long moment while he refuses to meet her eyes before she agrees. "All right, sweetie, if you're sure."

He wraps his arms around her, breathing in the scent of gunpowder and dust and time on her hair, and cannot hide his relief. "I'm sure."

...

But every day that he passes the TARDIS, it gets worse. It doesn't feel like enough - not enough time, never enough - and he can feel it slipping away from him every time River gives him a pinched, questioning glance.

The melancholy eats at him.

Maybe if it were a proper adventure - the two of them, running - maybe then he could enjoy the moment and just forget - no, no. That never works. He's spent too many of their adventures already either grumbling that it's their first time or lamenting that it's their last. He promised himself he wouldn't waste these moments - such precious scraps of time - these rare moments, just the two of them.

But River is as ill-used to living in one place as he is. They both get restless. They row over arguments decades past - over dinner plans and academic requirements - over her lecture material and his shoddy, distracted note-taking, often scribbled over in Gallifreyan with entirely inappropriate suggestions. They always make up after, breathless and desperate, but it's never enough.

When River walks into his converted study with her vortex manipulator strapped to her wrist, he can't say he's surprised. Though his hearts instantly plummet into his feet anyway.

River sets her jaw and he knows that this will not be a discussion. "I'm going out, whether you come or not, Doctor. It's too big a universe to spend on Luna."

"Where?" His voice wavers as he asks and he has to keep his head bent over his books so that River cannot see his eyes. Not the Library. Not yet. He's not ready yet. And he knows with absolute certainty in that moment that he'll never be ready. He'll never be able to properly say goodbye. He's greedy for her - selfish - he doesn't want eternity if it is without River.

"Well, I thought we might pick up some chips at Calderon Beta, for a start. Nothing like dodging all the other versions of us milling about - it might as well be our anniversary."

Calderon Beta. The Doctor suddenly feels lighter than he has in weeks. "I could use a new hat."

"And I could use the target practice."

But they're both grinning and River lets him grip her hand the whole time without comment. It's not a proper adventure, not quite - no danger on Calderon Beta beyond too hot chips and potential paradoxes if they run into their other selves - but the Doctor doesn't quite feel up to that anyway.

River seems to understand.

...

They're munching on chips in a tiny boat, far out into the pitch black sea, waiting for the stars to come out. They've done this enough times that there's unlikely to be any looming danger - not even drowning. River has remembered to pack extra oars in case the Doctor loses the first set, and he rather suspects she has a portable engine tucked away in her bigger-on-the-inside bag. He gets momentarily distracted by the idea of emptying both of their pockets to compare - he might have a spare engine or two in his own - when River shifts and makes a soft little sighing sound that immediately captures the Doctor's attention.

He glances up, chip in hand, suddenly alert, his good mood already a faded memory. There's no surprise (and it really would be a surprise, after the number of anniversaries they've spent on this water) sea monster behind him - he checks - and River has her eyes fixed on her lap. He thoughtfully chews his last chip as he tries to determine the best way to go about asking what's wrong - he's been married long enough to know that it's never straightforward with River.

"I miss them too, you know."

River's voice is deliberately soft, steady. He doesn't need to ask who she means. The Doctor swallows hard, forgetting about the chip and nearly choking into his next incarnation - and oh, River would kill him twice for wasting a regeneration like that. Sputtering to recover, he reaches out and covers River's hands with one of his. "I know."

River glances up sharply at his coughing fit, but her eyes quickly focus on his bowtie instead of his face. "They loved you, you know - you were their best friend - but they made their choice. Amy made her choice. They lived their lives, Doctor, and they were happy."

There's something about her phrasing - the Doctor meets River's eyes steadily. Oh River - his brilliant wife - busy trying to comfort him when he can see the hurt shining in her eyes. "They loved you too, River. You'll always be their daughter." She glances down, worrying her hands, a gesture he thinks she got from him, and he continues softly, "I'm glad they were happy together, River. Like us," he swallows, suddenly desperately needing her affirmation, "we're happy together, aren't we? I know I don't always say or do the right thing but-"

She cuts him off, mercifully, squeezing his hand as her lips brush his. "Of course we are. Besides, if we weren't happy, I would have killed you years ago, my love."

He can't resist tugging at his bowtie with his free hand and grinning at her. "You did. It didn't take."

A smile teasing at the corner of her lips, River shrugs easily. "Oh well, I guess I'm stuck with you."

They hear a splash somewhere off in the distance, and River laughs, low but genuine. The Doctor blushes and pretends to be irritated, "It's not funny. It took me ages to get my tweed dry."

Reminders of his clumsy younger self and happier times seem to have snapped River out of whatever melancholy mood she was in, and she meets his eyes gratefully. "Well then, you shouldn't have stood up in the middle of the boat, sweetie. Honestly, what did you think would happen?"

"I thought I was being romantic," he pouts, shuffling carefully toward her on the tiny ship that bears them.

"You got me soaking wet!"

"Did I now?" He can't resist smirking, just a bit, and River blushes ever so slightly at being the one caught out by an innuendo.

"Careful, I might decide to recreate that anniversary and throw you overboard." But she shifts to the side and lets him stretch out next to her, curling around him as they remember that long ago anniversary happening just beyond them in the mist. There's dozens of versions of them, spread out in boats across the same sea, tucked safely away in the low mist and waiting for the stars to light up the sky. Dozens of anniversaries, and dozens more on land - splayed across branches, waltzing through the tourist center, scaling the rocky mounts.

On this day, this small planet might as well be populated only by them. So many times that surely the paradoxes have folded in on themselves and somehow stabilized from the mess of them.

It's peaceful, in its way.

...

They settle into a surprisingly easy sort of domesticity that is uniquely them. He cooks every strange and fabulous recipe he's ever learned with the (often paltry) ingredients on hand in the kitchen. River sits on the countertops, polishing her various weaponry and proclaiming loudly that she will never eat that and where did you learn to cook, sweetie, honestly! He usually tells her stories about years he spent teaching famous chefs, as they debate whether or not a purple carrot-like-product is a viable substitution or who really came up with the Yorkshire Pudding. He convinces River to try whatever he was cooking anyway.

Half of the time they end up ordering take-away - which actually means dashing off in the TARDIS to some hole-in-the-wall restaurant that only existed in one particular century in a little corner of a country in a tiny corner of a planet in a miniscule corner of the universe. By the time they make it back, they are breathless from running, sometimes a bit singed at the edges, and they've usually completely forgotten about or stayed out far past dinner. Sometimes they don't come back for months, though they make sure to return seconds after they have left; the TARDIS landing while the echoes of her departure are still fading away.

Her neighbors hate him.

Though he can't understand why. Compared to River's target practice in the backyard, his tinkering in the garage can hardly be considered a nuisance. He's only blown it up twice. Okay, maybe three times. But that last one doesn't count - it's hardly his fault that they brought a hitchhiking Warg back with them from Cocharloid Prime and it chewed through the wiring of his latest thing-in-progress.

River just busses his cheek and tells him they'll have to host a dinner party for the neighborhood. Honestly, he couldn't think of anything that sounds less fun, but then River shows him the dress she's planning to wear. He takes great joy in stripping her out of that dress. And, well, the idea of watching her in it all night, knowing exactly what it's going to look like on their bedroom floor... is just too torturous and appealing to pass up.

...

He stays until staying feels like running away. Until the looks River shoots him out of the corner of her eye have almost found the words for questions he can't answer. Until he becomes melancholy, like it is all just a dream that is slipping through his fingers no matter how he scrambles to hold onto it. Because he already knows he will have to leave and face a world without River when he desperately wants to just stay here. For the first time in all his long lives, he just wants to stand still.

...

The end of the academic year sneaks up on him. He's been so caught up in River - in their adventures and their dinners and their strange little life here - that he's, once again, lost track of the calendar.

It's the message that first alerts him. The neat little electronic hologram, gamely reading out an announcement that he's met his requirements and just needs to submit his final dissertation.

He's already written it, of course, off on one of their adventures months earlier, but he'd rather forgotten about submitting it and it hardly mattered anyway when he was busy taking in River's lectures. But the message nags at him - an anxious tingling sensation building up until his mind finally latches onto the source of distress.

His degree is complete and the year - this year, their year - is coming to an end. The sadness that he's kept neatly tucked away rises up and swallows him whole. He's been running. He's been running with River to run as far from her death as he can. And his time is up. He can feel it in his too-old bones - a dragging pull that eats at him and tells him he's out of time, out of time.

The day he turns in his dissertation, River is waiting for him at home. He finds her in the backyard, lounging against the TARDIS doors, one hand pressed against the wood as she murmurs softly to his ship. She smiles when she sees him, but the way she kisses him - that raw edge of longing and desperation - tells him that she knows too. He kisses her harder instead, clinging to her. Tells her that they ought to throw a party - celebrate sharing the same degree. Suggests wild adventures they might go on - full of dusty old artifacts and possibly still quite alive old monsters.

River offers him a tight smile. "It was lovely to have you here, sweetie. Now, go off and save the universe before I stop it again, just to give you something to do."

He smiles weakly. "I don't want to go."

"None of that, my love. You have to go be the Doctor, I have to be River Song the Professor, and we can't always be those things together." She eyes his watery smile and grips his hand tighter, voice suddenly whisper-soft, "Just - don't leave it, whatever it is, so long next time, Doctor." And then she's letting go of his hand and striding away.


A/N: This is the end of part I. This story is in three parts, and I'm already posting the next chapter, so don't worry - this is definitely not the end!