He relives their goodbye in Sheffield over and over. Sometimes it's muddied with the conversation about his wasted talent outside her primary school. Sometimes it's the sound of her mum's voice commenting on how much he clearly cares for her. Each time he receives a letter from Jemma he relives that moment on the train platform. He hasn't said the words, but he's all but promised himself to her. He doesn't go out with his squaddies to the dance hall in Comrie when they have a night off. He doesn't chime in when they talk about the prettiest girls in the village. His platoon gets a new NCO who even assumes, despite the absence of a ring, that Fitz is married because he acts so little like a single soldier.

He looks at the date one day while writing Jemma and realizes it's been over two years since he joined the Territorials. Two years since he made the reckless decision in the spring of '39 to somehow spite and simultaneously please his father and become a soldier.

There had been a time back when they'd first been mobilized when he'd wanted to learn everything he possibly could about the unit he was serving in and the equipment they used. He had never spent much time around firearms growing up. So when he first joined the Highlanders he read every book and manual he could on how the Enfield rifle functioned. As their training intensified, he'd done the same with every new weapons system in the unit. Access to the Bren gun and Mills bombs was difficult, but he read what he could to learn all their components too.

That technical knowledge certainly helped him some, but beyond stepping up to fix the wireless or jams in rifles on the firing line, he's pretty unremarkable as a soldier. Just another Highlander in drab battledress flooding the fields of Perthshire. Perhaps it's Jemma's words back in Sheffield or perhaps it's the fact that her letters start to make more mention of Milton, whom Fitz is far too timid to ask about, that make him finally act on his ideas.

He wants to create something.

It starts with a visit to the company armorer and an inquiry whether there is a spare Enfield he can modify. The armorer has a laugh, only because based on his own performance and his own admission, Fitz is a notoriously bad shot.

"All the modifications in the world won't help you shoot straight," he teases.

"No, probably not." The dismissive way Fitz says it seems to pique the armorer's interest because he manages to find a rifle that hasn't been issued. He informs Fitz it frequently misfires and was going to be cannibalized for parts anyway.

"So I can have it?"

"Well, you can't leave the armory with it, but I suppose, yes, in here, it's yours."

Fitz grins and picks up the faulty rifle, looking over each section from the stock to the front sights with wonder. There are so many possibilities, so many variations and modifications he could make. Like anything, it all begins with research. He studies everything. For an entire week he focuses on only the barrel, its internal dimensions, conditions and pressure points. Then he examines the iron sights and the front and rear aperture. Improved accuracy should come first, after all. He fills a notebook with sketches on different trigger assemblies and action screws. He spends so much time there the armorer gives him a key to the shed so he can spend what free time he has working with the faulty rifle. There's so much he wants to write Jemma. His letters simply say he's learning new things without any additional detail, hoping she'll understand.

Only the armorer knows where he spends all his time. The old corporal insists on seeing the result of his first round of tinkering and, after two months, takes him to a makeshift range. Whereas Fitz is usually nervous on the firing line, anxious about qualifying and embarrassed at his ineptitude with a rifle, he is now remarkably calm. This feels less like shooting on the army's terms. This is testing something of his own creation. He fires three shots into a piece of cardstock 25m out, which by itself renders the armorer speechless. He demands to know what Fitz has done to keep the rifle from jamming when chambering a round. Fitz mumbles something about the magazine spring while he makes adjustments to the windage knob. While his shot group is far from perfect, the armorer's curiosity is piqued. He insists Fitz get on with it and shoot at the real targets further away.

Settling into a prone position, he takes several steadying breaths. Spare ammunition is hard to come by and he knows he has to make these shots count. He has to prove he's done something with the rifle if he wants to continue this work. Pulling back the bolt, he takes aim and squeezes the trigger at the bottom of his breath. The loud ping of the can, indicating he has hit the target over 300m down range, renders the armorer silent. Fitz isn't sure whether his speechlessness is due to Fitz's marksmanship or the fact that the rifle has now fired five straight rounds without jamming, but the next day he brings Fitz a Bren Gun that has been giving 8 Platoon fits. The following week it's a Webley revolver their company commander carries.

He finally reveals to Jemma that he's become the armorer's apprentice. Her questions, however vague she tries to make them, about the nature of his work still go unanswered, though he does his best to try to fill in her queries. He hopes she'll understand.

Her letters speak about the same banal activities. She'd gotten a trim and shampoo in town for 4 shilling and sixpence. She'd gone for a bike ride in the country and the village hop on Saturday night. They'd eaten Welsh rarebit on Monday. He finally learns Milton is a sophisticated Etonian who'd attended Oxford and majored in maths.

The frequent mention of Milton when discussing such activities just sends Fitz deeper into his work. In whatever free time he has, he works on whatever the armorer gives him, but the rifle becomes his singular focus. What began as a little tinkering here and there, begins to consume him. Fitz fills an entire notebook with pages of sketches and ideas.

The rifle begins to look less and less like the other standard issue rifles. He fiddles with ways to make it lighter and shorten the barrel, going so far as to read upon gunsmithing and to visit the town welder. He attaches a piece of leather to the buttstock to improve the recoil, removes the locking lug for the bayonet to improve accuracy, and even works on improving the stock bedding. His own issued rifle feels strangely unfamiliar in his hands when his unit conducts a six-day march. All he can see fit to tell Jemma in his letter is that he's made something truly great.

Knowing better than to ask questions about what he's making, she continues to talk about work. She talks about changing billets in July and complains about being exhausted all the time due to her shifts constantly changing. He tells her how glad he is for his new project, how it feels like coming out of hibernation after months, years even, of doing nothing. His brain is constantly working. Ideas come to him all the time, a different kind of round at breakfast, a muzzle modification at first formation. Sometimes it's a completely novel design for a new detachable telescopic sight he dreamt up while pulling sentry duty.

The threat of invasion seems to pass when they hear about the German invasion of Russia, but it doesn't do much to raise morale. News of defeat in Crete at the hands of vicious German paratroopers makes it difficult to stay positive and German bombing runs over to Clydebank still continue. Jemma speaks admiringly of the many women in uniform who work alongside her and Fitz senses the urge to do more come through in her letters from time to time. He wonders when he reads them if her words about wasting talent hadn't been rooted in her own frustration.

He's agonized for so long over what it is she actually does that her teary confession in Sheffield had been difficult to process. She makes no mention of it her own letters, but he knows how easy it is to hide the truth.

When his unit begins lending NCOs out to train the Home Guard, it is Fitz's turn to express frustration in his letters. As the oldest and longest serving soldier in his section, he's unofficially promoted to Lance Corporal and placed in charge of the two other privates. Maintaining accountability is a pain and he hates every minute of being in charge of anybody. Despite his constant reminding that it's only temporary and not official, Jemma and his mum both heap untold congratulations on him, their pride obvious in the words they write. He's prouder of the work on his rifle than on the two privates he has to babysit, but he knows he can't tell her more.

His unit's close work with the Home Guard brings into question the quality of the ad hoc weapons they use. The leader of the local volunteers, an aging captain who still wears his wool uniform from the Great War, argues that if they're meant to be the last line of defense should an invasion come, they really ought to be armed better. Word of Fitz's rifle modifications and work on the Bren Gun gets out thanks to the loose lips of the armorer. Fitz soon finds himself spending nearly the entire month of September working to improve and redesign cheap weapons for the local Home Guard units.

His work is so good it soon becomes his official duty. He misses a ceremonial detail at Glamis Castle, complete with a visit from the Queen and Princess because he has to assist the Home Guard in somehow turning two old World War I sixty-pounders into anti-aircraft guns. He writes to Jemma, simply saying he was no longer filling a Lance Corporal spot and had been pulled away for an additional detail. He can't let on that he'd much rather be tinkering on the old artillery piece than guarding a castle. He hates not being able to tell her the niche he's started to carve out for himself here. For the first time, he's beginning to feel like he has a purpose in the Army and he hates that he can't tell her why. All he can do is hint at their conversation in Sheffield and say it's no longer such a bad thing to be so cerebral in the army.

In the late sticky days of summer, his company finally leaves the town that's been their home for over a year to move into camp 160 km closer to the coast. He can tell Jemma nothing save the fact that they've moved. She'll figure it out when she receives his letter and sees the postmark. Fitz continues his duties with the the Home Guard, seeming to be more a part of their units than his own. His squaddies laugh when he hums along to a popular Noel Coward ditty about the Home Guard. It's a clever little song about the real shortcomings they face in munitions and equipment, about old veterans from the Great War fighting with an arquebus from Waterloo and a Vicar fighting with a pitchfork and a stave. The song gives him an idea. He writes some of the lyrics to Jemma, telling her they're his favorite lines and how he can't get them out of his head. He cites them in another letter, telling her he's been working with the Home Guard and hoping she'll put the pieces together.

She seems to miss his point and writes instead about her favorite lines from the song, which he's at least pleased to read she's heard. For some reason the thought that they're listening to the same songs despite being over 600 km apart comforts him. It seems to comfort her too because she begins writing him the names of favorite songs that help keep her spirits up. They're all songs he has heard, but Down Forget Me Not Lane and When They Sound the Last Clear take on a new meaning when he thinks about Jemma listening to them too.

Summer turns to fall and they leave Perthshire to take over from the Royal Scots in East Lothian, thirty kilometres outside of Edinburgh. He loves the thought of being so close to the place that had been his home for four years. All he can think about is asking her to come visit. They're billeted outside a pleasant seaside resort in a mansion with a fine ballroom. They have dances where the same songs Jemma has been sharing with him in letters are always playing. Each time Vera Lynn warbles about never being apart, he can't help but simultaneously think of Jemma and wonder whether he's a complete fool for doing so.

He hates being the one always suggesting they meet. Milton still hasn't disappeared from her letters. While his name rarely appears by itself and is usually accompanied by her other shift partners and what they'd done to amuse themselves that weekend, it still irks him.

Fortunately, his work is more rewarding than it's ever been. The jokes from his squaddies about being more a Home Guard soldier than a Highlander become reality. He's given an official posting to design and improve weapons for the Home Guard. He has his own garage where he works on everything from hand grenades to hunting rifles.

There's a degree of autonomy and freedom to his work. Sometimes it's converting shotguns and hunting rifles. Other days it's developing anti-aircraft weapons. One week he's even brought to a motor pool in Leithe where he's tasked with making improvements to an armored vehicle. Sometimes he works with mechanics, sometimes he works with a gunsmith, but mostly he works alone.

His official job is to help the Home Guard, but he's backlogged constantly with requests from soldiers in the unit. His visitors range from a private who wants him to fix a faulty compass to the battalion commander who wants a mount for a Bren Gun in his personal transport. Sometimes the requests are impossible with the resources he has, like the sergeant who requested glasses that would somehow allow him to see at night. He's simultaneously flattered and annoyed that his fellow soldiers think he can design anything. Though he explains to the sergeant that he can't possibly construct glasses like the ones he is talking about with the supplies he has on hand, he becomes obsessed with the idea of creating a telescopic sight that worked at night. The more fantastic ideas make him desperate for Jemma's opinion.

His letters can't begin to convey how pleased he is with the work he's doing. It gets wearing, describing the trivial details of his day, what he'd eaten for breakfast and the weather yesterday afternoon, but not the ideas that fill the pages of his notebooks.

The visits from the higher-ups start around the holidays. First it's a Colonel in the Home Guard then it's the Commander of Regional Command East, then it's a Polish officer.

"This is Private Fitz." Fitz overhears a young lieutenant say while clearly giving a tour to another high-ranking officer. "He's our little monkey. Keeps the whole Home Guard supplied and makes us anything we need." Fitz doesn't look up from the work he's doing until the junior officer barks at him that they have an international visitor. Fitz snaps to attention and waits patiently. Usually all that happens in these visits is he answers a few simple questions about himself and is left to work. He knows any time a private meets anyone above the rank of lieutenant it's usually a forgettable experience for the latter anyway.

This is an American however. Fitz wonders if perhaps that's why the junior officer is so eager to impress. It's the first Yank they've seen in Scotland.

"You build weapons for the Home Guard?" The American officer asks.

"Yes, sir."

"So are you the one responsible for the anti-tank guns I've seen all over this island?"

"I've made quite a lot of anti-tank guns, sir. Can you describe it to me?" Fitz remains at attention and the American officer scoffs and waves his hand in dismissal at the formality and tells him to relax. He describes a gun with a smoothbore barrel that fires a three inch shell about 300 yards.

"Sounds a bit like something I made back in August." Fitz scratches his chin. "Effective range of mine was closer to 1,000 yards though.

"1,000 yards?" The American officer whistles. "Who'd you make it for? Who'd you submit it to? The Ordnance Board?"

"The Ordnance Board?" Fitz laughs. "No, I just...work here. Sent it off to...whichever Home Guard commander asked for it."

"Do you have the schematics for it around here?" The Major seems highly intrigued.

"Probably." Fitz remains standing at ease and only after the Major motions for him to go search for it does he begin rummaging through his desk.

"The one being mass produced now. I'm pretty sure it's a structural engineering firm that designed it. They got a huge contract for it."

"Yes, well," the junior officer nearly interrupts the American major. "Private Fitz isn't - he's no structural engineer."

"No." The major takes the schematics from Fitz's hands and looks them over. His expression isn't hard to read. This American wears his emotions more obviously than any officer Fitz has ever seen. "I'd say he's worth about ten structural engineers. I can only make sense of...about half of this, but are these telescopic sights for use at night?"

"It's just an idea," Fitz mutters in embarrassment.

"How would this idea work?"

"Well, theoretically it would use an infrared light source to illuminate the targets. There'd be an anode and a photo-cathode in the tubes there. I think I could use a combination of cesium and oxygen for it - " Fitz can see halfway through is rambling that the officer doesn't have any idea what he's talking about. Still, he is smiling and he seems very impressed.

"You think you could really make that?"

"I don't know. Maybe. Not here." Fitz laughs, motioning around to the mess of a shop where he works.

The young lieutenant, now clearly annoyed at being upstaged by a private, seems eager to leave Fitz's shed.

"The Colonel is expecting you by 1300, Major Coulson. We ought to continue on."

The major shakes Fitz's hand. Then they're gone and he's back to being alone in his shop.

The encounter is intriguing enough that Fitz writes to Jemma about it. He tells her that he met an American officer. He tells her how affable and informal the man had been, disinterested in every military custom and courtesy. He tells her how interested he was in Fitz's work, even the most ridiculous designs that he'll never come close to building here. He knows she is desperate to find out what he is working on and is pleased when she asks in more than one letter when he'll be granted leave next.

She has two weeks of holiday this year and Fitz hopes he's not reading into the letter when he detects a hopefulness about how to spend it. She throws out numerous options that she and her friends are contemplating. He's pleased they don't all involve going to London. There's talk of a trip to Wales and more than one about journeying to Scotland. He feels his heart pound in his chest at the mere thought of her being here and reads the letter twice to make sure he's not imagining it.

There are no dates. Nothing is fixed, but she seems more keen on traveling to Scotland than anywhere else her friends have suggested.

How wonderful it would be to see you again.

His smile as he reads the words is so noticeable that the old armorer sees him and laughs.

"You get a thousand pound patent for that rifle or what?"

"Might have a friend come visit is all." He folds the letter up.

"Oh? That wouldn't be the same lass that writes you all the time?" the armorer continues to tease. As private as Fitz tries to be, it's no secret that his name gets called more than anyone's at mail call.

"Maybe." He's not trying to be coy with the vague dismissal, merely refusing to get his hopes up. He's heard the talk about the battalion moving again to do mountain warfare training. He knows better than to pin his hopes on staying here long enough so that his path might cross with Jemma's.

He's not sure how he even fits into his unit anymore. He takes his meals in the garage and spends all day away from the squaddies that he'd gone to France with. He technically belongs to the unit unit, but is apart from them in every way.

He's relieved when the official posting comes through. He wonders if it is the American Major's doing. He has no idea what unit the Major is with or who he is friends with, but Fitz is given an official posting as an enlisted advisor from 2nd Battalion working on weapons research. His pay doesn't change, nor does his uniform, but he leaves their garrison in Lothian and is instead billeted in Edinburgh above an ironmongers. He is still required to wear his uniform, but nothing else is at all like life in the army. His first line supervisor is a retired Commodore now serving in the Home Guard and he reports to a civilian named Clarke, who checks in with him weekly. It's a far cry from working in the armorer's shop with a supply sergeant.

As always, he can't tell Jemma much aside from the fact that he's moved again and has a new job. He does tell her it's the most he's enjoyed any job he's ever had. He wants to tell her it's even better than working in the armorer's shop or the lab in Glasgow, but knows he can't say much more.

He's getting paid to create things. All kinds of weapon systems. Every week it's a new challenge that Clarke brings him. Sometimes it's converting shotguns and hunting rifles like he has been doing for the last seven months, other days it's designing entirely new anti-aircraft weapons. Some days he gets to work on his night scope. Other days he's ordered to develop a new floating mine system. Major Coulson visits him each month. Fitz knows no more about who exactly the American officer is than he did in January. All he can tell is is that he's very interested in the work Fitz is doing and if Fitz needs any materials, no matter how outrageous, all he has to do is ask the Major.

Despite only seeing him once a month, he feels a sort of partnership and familiarity he's confident a private shouldn't with an officer of his rank. The Major asks about more than just how his projects are going. He wants to know what he does when he's not working, how he likes the city, what he does in his free time. Fitz admits that mostly he just reads books, writes letters, and thinks of new designs.

"What about your family?"

"Not much to know," Fitz dismisses. "Mum lives in Glasgow. Dad's with the Black Watch."

"What's the Black Watch?" Unsure whether the Major is playing dumb or, more likely, just ignorant about the British military, Fitz informs him that it's one of the most famous Jock regiments. "Regular Army or Territorial?"

"Regular."

"So your dad's always been a military man?"

"Aye, he was a lieutenant at the Somme," Fitz mutters.

"Is that why you joined a line unit?" The inquiry reminds him of the tense conversation with Jemma in Sheffield about why he'd joined the infantry. "You said you joined before the war began in, what, '38? '39?"

"Just wanted to do my part," Fitz shrugs and gives his usual answer. "Knew war was coming."

"Well, this is clearly where you're meant to be." The major claps Fitz on the shoulder and exits the workshop. "I'll be back next month!"

Fitz comes to look forward to the visits. The major brings more than just requests. He brings materials Fitz requests along with detailed information about American activity in the Pacific. Sometimes the equipment he asks Fitz to design is clearly meant for jungle warfare. Sometimes it looks like it's meant for the desert. Sometimes it's schematics of a missile and other times an amphibious tank. He wonders who he is really designing the equipment for, but he doesn't dare ask questions. He's gotten good at that.

The only problem with his posting in Edinburgh is that mail is slower to get to him here. They only bring it once a month, but each month there's always a giant stack of letters from Jemma. She has met an American too. It takes over five weeks of being jealous over both Milton and Bobbi before he learns that the latter is a woman in the U.S Navy who has come to work with them.

Jemma's letters drip with admiration for the woman who speaks five languages and knows self-defense the same way his letters probably speak about for the kindley American officer that brings Fitz chocolate alongside containers of cesium and aluminum alloy.

He drops enough clues about where he is that she knows he is in Edinburgh. She asks how much it has changed since he was in university and what is still familiar. He knows she probably wants to ask about his work as badly as he wants to ask about hers, but simply says she's happy he's doing what he loves.

She mentions her upcoming holiday in every letter. One week she wants to show Bobbi London. The next she has a young coworker, who is scarcely more than a child, traveling to Scotland alone to visit family. The name of her colleague isn't one he has ever heard before and it all seems too fortuitous. Her young colleague doesn't want to travel alone. Bobbi wants to see Scotland. He doesn't know how much is Jemma's own intervention and how much is fate, but he has to read the letter four times over to make sure he reads it correctly.

She's coming to Edinburgh.