I've used dialogue from the show at the start of this chapter.

Mary sat at her desk, waiting apprehensively for Tom to arrive, knowing he was going to be angry with her for what she'd done to Edith that morning, deliberately and spitefully spilling the secret to Bertie that Marigold was Edith's illegitimate daughter. She heard his footsteps and straightened up in her chair, determined to front it out.

He came in and stood inside the door, scowling at her. 'Well, you got what you wanted. Bertie's left for the train and now Edith won't be the next Marchioness of Hexham.'

She stared at him, knowing she deserved his censure, but unwilling to bend to it. 'Well, that's not what I wanted,' she said, petulantly.

'Isn't it?'

'I still can't believe she'd never told him. How was I to know that?'

Tom came closer, visibly simmering with anger. 'Don't play the innocent with me.'

Mary stared up at him, guilt making her defensive. 'I didn't mean-'

'Don't lie!' he roared. 'Not to me. You can't stop ruining things. For Edith, for yourself. You'd pull in the sky if you could. Anything to make you feel less frightened and alone.'

Mary's temper spiked, needling her into answering peevishly back. 'You saw Henry when he was here. High-handed and bullying and unapologetic. Am I expected to lower myself to his level? And be grateful I'm allowed to do so?'

'Listen to yourself,' Tom sneered in disgust. 'Lower yourself to his level. You're not a princess in The Prisoner of Zenda!'

'Oh, you don't want to understand me!' Mary bit out, banging her hand on the arm of the chair in frustration.

'You ruined Edith's life today!' Tom bellowed, making her jump. 'How many lives are you going to wreck just to smother your own misery?'

Mary had had enough. How dare he say that when it was his fault she was miserable in the first place? She leapt to her feet, making to push past him. 'I refuse to listen!'

Tom blocked her way, getting in her face. 'You're a coward, Mary. Like all bullies, you're a coward.'

Then he turned his back on her, heading for the door.

'I'm a coward? That's rich coming from the man hiding behind his dead wife!' she shouted at him, stopping him in his tracks.

Tom turned around slowly, fury on his face. 'What did you say?'

'You heard me,' Mary snapped.

'Oh, so it's my turn, is it? You've pushed everyone else away and now it's my turn.'

'You're the one pushing me away, Tom, not the other way round!'

'Why? Because I won't sleep with you anymore?'

'Because you won't let us be happy! Instead, you've tried your damnedest to push me at Henry!'

'And now he's left you high and dry, you're lashing out at the rest of us. If he's gone, Mary, you've no-one to blame but yourself.'

'How many times? How many times do I have to tell you before you believe me?' Mary shrieked, frustration boiling in her chest, angry tears welling in her eyes. 'I don't want Henry! I never wanted Henry! He's gone because I spelled it out to him that I will never love him.'

'So now you want to pick up your consolation prize again, is that it?' Tom snarled.

Mary gaped at him, stunned. 'Is that what you think you are? My consolation prize?'

'Aren't I?' he snapped, bitterly. 'At least be honest about it, Mary. All I've ever been is a safe way to scratch your itch when there's no-one else around. I'm nothing more than a handy release valve to you.'

'No, you're not! That's not even remotely true!'

'Don't lie to me! Just don't! Not about this. I can't be your release valve anymore! I can't be the man you come to for sex while you're waiting for the real thing to come along!' Tom yelled at her, practically vibrating with rage and hurt.

'I'm not just a convenient outlet for your sexual frustrations, you know. I'm not a machine or a toy for you to play with whenever you feel like it. Believe it or not, I've got feelings too and I can't switch them off anymore. I haven't been able to do that for a very long time. So, don't think I'll come running next time you feel the urge to scratch an itch because I won't! I won't sully Sybil's memory anymore just to be your plaything!'

Mary stood there with her mouth hanging open as he turned on his heel and stormed out of the office, slamming the door behind him.

'Oh, Tom,' she whispered to herself as suddenly everything became a lot clearer. 'You stupid, stupid man.'

Mary blew out a long breath, preparing herself for a conversation that might just change her whole life. She knocked on Tom's bedroom door, opening it without waiting for an answer.

'May I come in?'

Tom was slumped in the chair by the fire, his head propped on one hand, a glass of whiskey in his other hand, a picture of utter misery. He didn't even bother to look at her. 'Go away, Mary.'

Mary ignored that, stepping into the room and shutting the door behind her. 'I can't. There's something I need to say to you.'

He closed his eyes. 'Mary, please. I'm not in the mood for another fight.'

'I'm not here to fight.'

Tom hauled himself up in his chair, leaning forward, rubbing his hand over his face and sighing. 'Fine. Say whatever you've got to say then leave me in peace.'

Mary crossed the room, dropping to her knees in front of him. Tom reared back, setting his glass down on the occasional table beside him, looking at her warily.

'Those things you said this morning made me think and I realised there's something I need to tell you,' she said, softly. 'Something I should have told you a long time ago.'

He stared at her, a guarded look on his face.

'I love you, Tom. Not as a friend or a valued member of the family and certainly not as a brother-in-law, although I have loved you as all of those things over the years. But now I love you. I am in love with you.'

Mary reached out to grip his hand, gazing up at him.

'For so long now, I've thought of Matthew as the love of my life, but I was wrong. He was the first love of my life. You are the second. And I realised this morning that you didn't know that, and it was causing you pain. You've never been my plaything. You've been my partner, my lover, my rock, my conscience, my anchor. So, Tom, I'm telling you now that I love you with my whole heart.'

Tom gazed at her, biting his lip, wetness shining in his eyes. He let out a single, strangled sob and Mary knelt up, pulling him into her arms. 'Oh, my darling.'

Tom's arms went round her, hugging her tight, his head buried in the crook of her neck. Mary stroked her fingers through his hair, holding him as he composed himself.

He pulled back, swiping his fingers across his eyes. 'Is this you telling me the truth, Mary? Because if you're not…'

'Every single word of it is the truth.'

'I thought this was just about sex for you.'

'It was at first, but it hasn't been about that for a very long time now. And I think it's the same for you, isn't it?'

He held her gaze, searching her face. 'Yes.'

'Then you do love me?'

He nodded. 'Yes, God help me. Yes, I do.

'Oh, thank heavens for that!' Mary whispered in relief as Tom gathered her close and kissed her. She kissed him back then pushed lightly on his shoulders to get him to release her. 'Say it.'

He smiled shyly at her. 'I love you, Mary Crawley.'

'Say it again.'

'I love you. I love you, I love you, I love you.'

Mary fell on him, wrapping her arms around his neck, kissing the life out of him.