A/N: Right. This is an idea that I've had brewing for a long time. One of those scenarios I've happily played in my head but always thought it was just a little too exaggerated to feasibly work in fanfic.

This week, I had a flash of inspiration (thank you, Fall of Giants, Ken Follet and Dan Stevens!) for how I could make it feasible. Yay! And was newly inspired to write this, thanks as well to masses of encouragement from Eolivet.

To set the scene a little, it's going to be an extensive AU (clearly, now) from the end of series 1.

If you'll allow me to claim now that though, certainly for this chapter and maybe the next, this will possibly seem a bit "Oh, here we go again" - I promise that it leads into a completely original idea, and that really the "Oh here we go again" part of it is really just a drop in the ocean to set up what will come after, which is really the main point of the fic.

Basically, I'm asking you to bear with me through this chapter! It is absolutely not just another 'post ep 7 fix-it' scenario - it will extend and develop into the war in a very AU manner.

Erm.. I do hope I haven't just really put you off! Enjoy! :) (Oh, and I promise I haven't forgotten about A New Dawn - I'm just waiting for the inspiration to strike!)

All That Is Left

Chapter One

The atmosphere around the breakfast table that morning was subdued.

The atmosphere in general had been subdued for a few days now. Though nothing seemed so very different, yet, the very shadow of war was dark enough to dampen spirits. The fact was, there was a war on – and the very awareness of that, despite its lack of manifestation to Lord Grantham's family in any real form yet, made anything other than an attitude of melancholy seem quite out of place.

Mary was glad of it. It meant the air of gloom that hung about her seemed in keeping with the mood of everyone else. It allowed her an excuse, gave her something to blame her despondency on.

With little enthusiasm, or appetite, she shunted her eggs around her plate with her fork. Occasionally Sybil would glance at her. Mary imagined she knew full well that it was not the war that troubled her. She was beyond caring. She wasn't sure she could care about anything anymore. Her heart was too shattered and empty to care.

Of course, it was not as though she didn't deserve it. She'd treated him terribly, she knew that. It almost made her anguish seem bearable; repayment for her repeated idiocy. Matthew was well rid of her.

Spearing a morsel and lifting her fork to her lips, she looked up with only passing interest as her mother entered the room. She uttered a mumbled greeting before nibbling disinterestedly at her food.

"Good morning, dears," Cora murmured as she breezed along the table to where Robert was seated. Mary's awareness was piqued; her mother sounded unusually distracted. She listened with half an ear as she continued to push her food around.

"What is it, darling?" Robert had also noticed his wife's manner.

"Carson just passed this to me, outside," she held out a sealed envelope to Robert, who looked up enquiringly as he took it. "It's been delivered from Crawley House."

Instantly, Mary looked up, her fork halfway to her lips. Slowly, she lowered it as she watched her father open the letter and read it, a deepening frown on his face. Why on earth would Matthew – or Cousin Isobel, for that matter – write her father a letter?

Robert's face paled.

"Good God," he whispered, voice hushed. Beside him, reading over his shoulder, Cora's face turned ashen.

As Robert continued to stare at the letter, Sybil leaned forwards slightly and frowned.

"What is it? What does it say?"

Mary was relieved she had asked. Her blood was running cold at the sight of her parents' faces.

"It's Matthew." Robert shook his head in resignation and sighed deeply. "He's… gone. Already, by the looks of it." He tapped the letter with the back of his fingers. Mary's heart thumped in her chest.

"Gone?" She whispered breathlessly. He couldn't have… Of course, he had said that he would, but not so soon? Surely!

She felt the blood drain from her face as her father met her eyes coldly. He looked saddened, but beyond that, she could have sworn that she could see the slightest shadow of accusation in his gaze.

"Yes. With the intention of –" he glanced at the page. "– buying a commission into the army. He's going to France."

"Oh…" Sybil breathed, eyes wide in shock. Edith's brows rose in almost amused interest. A moment's silence hung over the table as they each processed the implications of Matthew's letter. Oh, Mary had resigned herself to the fact that he would leave, but she had not for a moment thought that he would so rashly throw himself at the army! Matthew. The army. The war. The things seemed incompatible. Matthew was dear, kind, gentle… A solicitor. Peaceful. A soldier, he was not. It didn't make any sense.

"But that's ridiculous!" She eventually spluttered. "He can't possibly –"

"I assure you, he can, and he has!" Robert said sharply. Mary glared. How could he do this? The panic she felt was only compounded by the stirring of guilt in her stomach. He would have stayed… Of course… If, if… She had driven him away. He had left because of her. She felt sick.

"What reasons does he give?" Edith asked. Mary was not oblivious to her tone that clearly hoped for the blame to be laid at her feet. "It does seem awfully rash, even for Matthew."

Robert glanced back over the letter, and seemed to wilt a little. His voice quietened.

"It seems he wants to… do his part." The words dripped from the Earl's lips. "He just wants to do something. To make his own decision and follow it through." He suddenly looked weary, aged. "I'm not sure I can blame him." It had been hard for the young man, these last few weeks – so very hard. He'd done admirably well to deal with the turmoil thrown at him by… Cora's pregnancy (his heart ached a little), and had certainly not been helped by his eldest daughter. Yes, he could very well see why Matthew had leapt to the call.

"Oh, Robert…" Cora said softly.

Contemplative silence filled the thick air. Matthew, going to war. Now, it was real. It was here. It affected them. And it was her fault… Mary bit the inside of her lip hard, frowning at what was left of her largely untouched breakfast. It wasn't right. It wasn't fair. It should be she being punished for this mess, not him.

"Papa, you must do something," she implored firmly, turning her eyes to plead with him. "You can stop him, surely?"

"My dear, there's nothing I can do. He left on the first morning train – he doesn't even say for where."

"But that's not –"

"Mary," he warned.

"What?" Mary stood with a sudden surge of resolve, shunting her chair back, earning raised eyebrows from her mother. "I'm sorry, Papa, but if you won't try to stop him then I shall."

"Mary!" Cora exclaimed.

"I shall!" Mary could hear her own voice rising in her ears. She sounded wild. She was reminding herself worryingly of Sybil in her foolishness, but she couldn't seem to stop herself now the thought had entered her head. Her heart was racing. Matthew couldn't join the army. He couldn't. It was her fault, and it was imperative that she at least try to right this terrible wrong. She had to at least try…

"And what do you think you are going to do to stop him?" Robert rose to his feet also, leaning forwards with his hands on the table. He felt dangerously as though her were losing control over his daughters.

Mary clasped her hands in front of her, twisting them nervously. When she spoke, her voice at least was impressively calm and firm.

"I shall find him. I'll beg him, if I have to. And if there is nothing I can do, then at least I shall have tried." Her voice trembled a little, then. Her determined glare melted suddenly to an expression of sorrow. "I must – I must speak to him, Papa."

Robert opened his mouth to rebuke her stubbornness, but Cora understood the look in Mary's eye and laid her hand on his arm. His expression softened a little, and he looked sadly at his daughter.

"I think it's a little late now for that, Mary… Don't you?"

She knew perfectly well what he meant. But he didn't understand that that, more than anything, was why she simply couldn't let him leave. She may have realised too late how much she loved him, but at the very least now she knew he deserved to know the truth, if it could save him from this folly. And if it really was too late… She couldn't bear that he might go to war, when they had parted so terribly. He had to understand.

"I know it only too well," she replied with a sad smile. For a long moment, their eyes were locked in a silent argument. Eventually, Robert leaned back a fraction.

"You'll take Branson."

Mary sighed in relief at the small victory. It was the first step.

"I'll be perfectly fine on the train."

"You will take Branson, Mary."

"Oh, Papa," she sighed with a shake of her head, even as she left the dining room. "When have I ever done as I am told?"

In very little time, Mary was ready to leave. Nothing on earth would have stopped her. No matter how determined Matthew might be, she was even more determined, now. A hasty discussion with her father had led her to decide that Manchester was likely where he had gone; York was closer, but they could far more easily imagine him returning to his old home to sign up, certainly now. As she strode briskly to the front door, pulling her gloves on, her father appeared from his library and stopped her. Taking her arm, he looked seriously and fondly into her eyes.

"I do hope you find him, my dear, and work out what it is you need to." Mary smiled gratefully. He continued, pressing something into her hand. "You'd better take this – if you ask about him at the recruitment office, they won't simply hand out his details to any stranger."

Mary nodded, with a small, weak smile. Robert kissed her cheek, and without another word she hurried out of the door and into the car. She was grateful to her father; a calling card with her name and address, of course, would prove her connection to Matthew to anyone that asked what business she had in seeking him.

Before long they reached the station. Branson turned in his seat, looking back pleadingly at Mary.

"Are you sure you won't allow me to accompany you, my Lady?"

"Quite sure, thank you, Branson." Her resolve was clear. She didn't need him, had already promised her parents that she would telegram them with any news. She was perfectly capable.

"Alright. Well, good luck with it, my Lady – I do hope you get what it is you're after."

"Thank you," Mary gave the chauffer a warm, sincere smile.

Manchester was loud, dirty, bustling. Mary's eyes widened as she left the station, beginning to wonder if perhaps she should have allowed Branson to come after all. But no, she was determined to do this alone. She wanted no audience to her failure, if it came to that – and no-one but Matthew to share her success, if that would be the case.

It was not so very different to London, she told herself as she strode purposefully down the wide, busy street. The recruitment office was not hard to find; though it was only a few days since the outbreak of war, the push to enlist was already fierce. Signs plastered to every wall showed her the way, and soon she saw the long queue of men trailing out of the door.

Her heart leapt. She may still be in time.

Keeping some distance to try and look as inconspicuous as she could, she walked down the side of the line, tracing each face carefully. Her eyes fixed upon every head of golden hair, but no, that was not him, nor that… As she drew nearer the front of it, the pounding of her heart in fear grew louder. She reached the front. He was not there. She looked back, searching the line again, desperately… No.

Fighting down her rising apprehension, she walked as tall as she could to the little rostrum by the entrance. A man in uniform was taking down the details of young man of barely twenty. Mary waited, shifting restlessly, until the youth was ushered inside, then she rushed to the uniformed man.

"Excuse me –"

"Pardon me, Miss, you're not wanting to sign up are ya? There's a queue, you know!" The man who had been next in line shouted in affront.

"I'm terribly sorry, I'll only be a moment," Mary said, raising her hand in a dismissive wave of apology with only the barest glance back at the man. "Excuse me," she said again to the man behind the rostrum, who was tapping his fingers on the top of it. His brows were raised in perplexed amusement.

"Yes?"

"I believe my cousin came here today with the intention of buying a commission. Could you please tell me whether he's done so already? His name is Matthew Crawley." She gestured down at his little book, already bursting with names. The man's brows rose further.

"Is that right?" He peered doubtfully at her, but his demeanour changed immediately once he saw the name Lady Mary Crawley and the address of Downton Abbey on her card. "'Let me see, Milady." He scanned through the book, running his finger down each page. Eventually he nodded. "Ah, here we are. Yes, we had a Matthew Crawley sign up this morning."

"Oh." Mary gasped a little, resting a hand on the edge of the rostrum and gripping it lightly. She felt faint. She was too late. Always, too late.

"Is… there anything else, Milday?" The soldier asked when she showed no sign of moving. The men behind were growing impatient. Mary blinked, fixing him with a demanding gaze.

"Yes. What might his next step from here be? Will he leave right away?" Her heart was in her mouth.

The officer shrugged. "He'll be sent down for training Friday." It was Tuesday.

Mary nodded. "Thank you," she smiled gratefully.

Her mind whirled. Too late. What now? She utterly refused to have come so far for nothing. He was going to war… Matthew. She would not let him leave – would not, could not – without him knowing it. It was too late for her to hope for anything now, she knew, but… She simply couldn't bear the thought of him leaving to fight – Matthew! – believing that she hadn't cared for him. If he were to…to… She couldn't even finish the thought.

For a little while, she simply stood there, looking around her at the tall, overshadowing buildings. If he did not leave until Friday… From his letter, she understood that he had no intentions of returning to Downton in the meantime. A hotel, then…

By the fourth hotel, Mary had worked out a little routine. It had a sort of sick irony to it, she thought wryly. But it seemed the easiest way.

She moved elegantly up to the desk and rang the bell. Several moments later a short, balding man appeared. He folded his hands and surveyed her.

"May I be of assistance?"

"Yes, thank you." Mary smiled her most charming smile. "My husband is attending a conference in the city; I've brought some papers he left at home this morning – how remiss of him!" The steward smiled thinly. Mary took a breath and continued. The lie slipped out quite easily, now. "He also – dear thing – quite forgot to tell me which hotel he'd be staying at. His name is Matthew Crawley." She raised her eyebrows hopefully. To pose as his wife cut her deeply, but it was the only way to find anything out, she had quickly realised. She produced her card and waited, praying that this time… This time…

"Of course," the man eventually proclaimed with an air of authority. "Yes, I know the gentleman. He checked in an hour or two ago."

"That's wonderful. Thank you. At last!" A deep sigh of relief left her as she smiled tremulously, already emotionally exhausted. "Now, where might I find him?"

"I shall take you to his room, Milday."

Mary's brows rose. His room… She had not expected… Though, she supposed she had declared herself his wife. She trembled, in trepidation and shame at herself as she followed the little man up a flight of stairs and along a corridor. Every step brought her closer to him. His room… She had thought that she might send a message up, he would come down to meet her, though she had hardly believed that he would… And, she reflected, this was a conversation she would rather conduct in private. She clutched nervously at her linen skirt as the steward stopped in front of a door.

Once, twice, he rapped sharply. Mary hung back. She couldn't breathe. She wanted to run away. But she was here now, and it was too late… Always too late. Her pulse raced.

The door clicked open a little. Mary could only see his hand, his fingers curling around the edge of it, the tip of his nose when he leaned forwards a little.

"What is it?"

"Pardon me, Mr Crawley. Your wife is here, I have taken the liberty of showing her straight up."

Mary winced.

"My wife?"

As Matthew exclaimed in utter astonishment, he swung the door fully open.

Mary.

He visibly flinched, buckled slightly, when he saw her. In that moment, a look of indescribable anguish passed across his face. Mary's heart panged, guilt and regret pooling in her as she looked at him.

It was only a moment. The steward stood between them, a physical barrier, a blockade. It would not do to draw attention to anything untoward. Through gritted teeth, Matthew kept his eyes fixed, burning, on Mary as he dismissed the man.

"Thank you. That will be all."

With a slight bow, the man turned and hurried back along the corridor.

"Matthew –" Mary took a tentative step forwards, bursting with sorrow at his expression. His lips were downturned in anguish and his eyes glittered harshly.

"My wife?" He repeated, his voice dangerously low and shaking.

He shook his head, stepped back. And shut the door in her face.

TBC

A/N: Thank you for reading! As always I'd love to know what you think - reviews make my day!

On a slight historical note, in case you were wondering - I remember reading in a s2 article that "enlisting" referred to men joining the lower ranks of the army - officers, as Matthew would be, would pay for a commission. Anyway, that's as I understand it, hence that term appearing here - though I will stand corrected if anyone knows better!

Thank you! :)