This was written for Apollo888 as part of patsan's Matthew/Mary Secret Santa exchange 2013.

I haven't written in a really long time…the end of Season 3 sort of crushed my enthusiasm. I hope this is any good, and that you all enjoy it. I had the idea more than a year ago, that a conversation like this one should have happened between Seasons 2/3, and that if it had, some of the ridiculous drama between them wouldn't have been so ridiculous in Season 3.
Anyway, happy holidays!
Emily

She steps out into the same garden where he'd once walked out of her life for nearly three years, briskly wiping the tears from under her eyes. She doesn't expect him to follow her; in fact, she'd specifically told him not to.
So why does it sting so much when several minutes pass and she does not feel his presence?
Because what I said was cruel, but what I did was walk out crying, she answers herself. He should know which one to follow by now.
She shakes her head at her own foolishness, assigning so much responsibility to Matthew and allowing so much self-pity.
She's tired of having such wretched timing about Matthew, like the clocks that set their fates run half a tick apart. She'd thought that was finally over, but apparently not. The panic rising somewhere in her chest feels eerily like what settled in her when he withdrew his proposal all those years ago. He quite suddenly vanished from her future, and the dread that blossomed deep in her chest gave her the answer over which she had agonized for so long.
She presses her hand to her breast and breathes deeply. He's here, she reminds herself, though it's hard to do when she's just pushed him away, he's here.
The atmosphere shifts, in that moment, and there's the blessed sound of a breathing pattern she'd know anywhere.
She doesn't turn or speak.
"Mary darling are you all right?" he asks, and she almost crumples right then, her fists clenching. Oh, why does he have to be so infuriatingly good to her? But the fight isn't entirely gone out of her yet.
"What trouble is it to you?"
"Mary," he warns.
She sighs and shakes her head. "Shouldn't you be angry? Shouldn't you be…I don't know…defending your position, or insulting my opinions as a woman, or threatening to…" break our engagement she trails off, because of course she already did that to him. God, she hates herself for hurting him so, and it almost makes it worse that he doesn't hate her for it.
Matthew's face breaks into a rueful smile. "Mary, the days in which you could do something to truly vex me and think I'd take it at face value are long gone. I know you too well."
She glances at his face for no more than a second, then looks back onto the grounds. He waits.
"He's going to do it," Mary breathes. "I received a letter this morning; he's seen news of our engagement—how could he not?—and he's going to publish." She laughs bitterly. "What a story it will make! Reputedly cold eldest daughter of the Earl of Grantham not warm enough to keep foreign visitor alive in her bed; to marry family's unfortunate heir in cover up. What a pretty penny he'll make on that one. And he'll ruin you in the bargain."
He takes a determined step toward her, reaches out his hand. "So let him."
Mary crosses her arms across her chest, pointedly ignoring his offered hand. "Matthew why must you be so dense about these things?"
"I'm not. Mary, I'm not. I love you, and you're going to be my wife, Sir Richard Carlisle and his paper be damned." He takes a slow breath. "But surely you knew I would say that." Understanding dawns.
After a few moments of silence, he confesses, "It scares me too, you know."
She hums her question at that, her carriage polite; she's still not giving in.
"Us," he says. The flicker in her eyes tells him that he's hit on something.
He steps cautiously closer, and breathes in with relief when she allows him to take her hand, the stiffness of the muscles in her arm and wrist and fingers relenting a little under his touch.
"We have it in us now to destroy each other's happiness," she says. And they do. Now that they've acknowledged their feelings, there's no going back.
He bites his lip and nods, taking his place next to her as they stare out into the darkness together. "We have the power to create it, as well," he reminds her. He studies her for a moment.
Her brow furrows. "I'm so afraid that something else will happen. That we'll fight and I'll ruin it. That I've already ruined it."
"I'm here," he reminds her.
"Yes."
He sees the pain in her expression. "It was my fault, really," he says, "for ignoring my feelings for you, for letting you become engaged to that man, for angering him."
Mary bristles. "Oh for God's sake, Matthew, do stop falling on your sword."
She sees his face fall and finally reaches for him. One gloved hand slides onto his jaw and neck; her lips brush his forehead. She meets his gaze. "You are a good man, Matthew Crawley, but someday, you must learn that that does not mean you must carry the guilt of the world on your shoulders."
"I…," he trails off, lets his eyes drift shut. "We'll both have to learn to be happy, then." He lets a long-suffering sigh escape, hopes she'll laugh. "And I'll…try not to be so self-sacrificing."
She chuckles, allowing herself to enjoy his presence and the way he manages to make her smile. "Thank you for coming to find me," she says. The words feel dangerous, like part of her deepest heart has broken off and floats in the space between them. How strange it feels, choosing to be vulnerable. "You're quite bright, you know, for a country solicitor."
He grins. She sees her words sink into him, and feels lighter.
It seems her love has made her brave.