A/N: Hello! I posted this to Tumblr yesterday (do look for me on there if you're on it!), but someone asked if I'd be posting it elsewhere so I thought I'd pop it on here too, to be with ATiL.

I must admit that this started off as something very, very different in my head. Matthew was going inside to find Mary, and, well... different things would have happened..! But on his way in, Mabel popped into my head, and wouldn't stop talking, and this happened!

I very much hope you enjoy it. I have far too much to do but I can't seem to stop myself with these!

Set a year or two after the epilogue.

Do You Promise?

Matthew took a deep, deep breath, a happy smile on his face as he strolled up the path towards the abbey. Isis hung at his heels, scrabbling in the dust of the path every so often before barking for his attention. He scratched fondly behind her ears. Pleasant sunshine beat on the back of his neck, and he pulled his cap off, squinting a little as he peered up at the dusty, familiar stones. Home.

He imagined Mary would be in the drawing room - it was such a beautiful day, he'd half a mind to see if she wanted to come out with him - he was feeling hot and sticky from his walking but he wouldn't mind going out again, for the pleasure of strolling with her arm in arm.

Behind him, distant little thuds and clops grew steadily louder, and closer, and just as he passed the bench and the Cedar where so often he'd sat with Mary, a little cry alerted him to turn.

"Hello, Papa!"

"Well, darling! Have you managed to go without falling off today?" He grinned as Mabel drew up beside him on her dapple-grey pony, sitting proudly up straight in her riding clothes, with Lynch following dutifully some distance behind. She looked so grown-up! And even managed to hold the pony steady as Isis bounded up until Matthew held her collar more firmly.

"Oh I haven't fallen off for such a long time - oh, Isis!"

"I know, darling, I know." He smiled indulgently, walking alongside as they reached the front of the house. As they drew to a stop, he reached his arms up and swung Mabel down, chuckling as she didn't let go once he'd set her down, only wrapping her arms tighter around his waist with her cheek pressed firmly to his side. "Thank you, Lynch," he smiled as he rubbed her back, nodding at the groom.

"Very good, your Lordship. Lady Mabel's getting on very well, very well indeed."

"I wouldn't expect anything less!"

Mabel grinned up at him, then hugged him again, until the persistence of Isis's nose butting up against her hip caused her to break away and turn her attention to her favourite dog, chasing her for a little while with delighted laughter until she found a stick to throw at the edge of the gravel.

Smiling, Matthew settled himself down onto the doorstep, leaning back and slinging his arm over his knee as he watched them play, the warmth of the late afternoon sun glinting golden on Mabel's fair hair. Eventually, exhausted by Isis's boundless energy, Mabel ran back to her father and flopped down beside him, curling against his side as Isis nuzzled onto her knee. With Matthew's arm tucked snugly around her shoulders, the three felt very content indeed - and when Carson came out at one point, though it was dreadfully improper to sit slumped so over the doorstep, even he couldn't find it in him to begrudge them the leisure.

"Papa?" Mabel asked, twisting around to rest her head on her arm on his bent-up knee.

"Yes, Bel?"

"This is nice, isn't it. I do love you."

Matthew chuckled warmly. "Very nice, darling. Though we'd better not let Mama see the state of your riding dress, not before it's been to the laundry…"

"Oh…" Her face fell for only the slightest moment before Matthew tickled at her nose, making her wrinkle it up happily. "Papa?" she said again.

"Yes, Bel?"

"Grandpapa… He was Mama's papa, wasn't he?"

"Yes, he was. Have you been thinking about him? You know we miss him very much." It had been a couple of years now, since Robert had passed away, but Matthew supposed Mabel hadn't been all that young to forget him so soon. Not at all.

"A bit," she shrugged. Matthew got the feeling there was more to it than that, so he waited a little while, twisting one of her golden curls fondly between his fingers until she spoke again after a deep breath. "Do you think Mama and Grandpapa ever did this?"

She looked so serious, and the image she conjured was so silly, that Matthew couldn't help but laugh.

"I - oh, I don't know! Perhaps you'll have to ask Mama. I didn't know her when she was little like you, so I can't answer you very well, you see."

"Oh. Alright." Then, "Do you think they loved each other just as much as you and I do, Papa?"

He smiled adoringly. How he loved his little girl!

"I'm sure they did, darling, yes."

"That's an awful lot, then," Mabel grinned happily, hugging her arms around his knee a little more.

"Yes, it is."

"But -" Mabel frowned, her bottom lip pouting out a little as she wondered about something. Matthew watched her carefully, waiting for her, wondering what could be on her mind. She was such a puzzle, a wonderful little puzzle.

She sucked in a big breath and looked squarely at him, her clear blue eyes gazing into his, which reflected them entirely. "There was that time when they weren't very friendly. And they didn't seem to get on. Mama was sad at him, and it was like he didn't like us, Papa - we didn't see Grandpapa and Grandmama for such a long time! What about then?"

"Oh, my little darling…" Matthew sighed, his gut twisting a little at the memory of that horrible time. He'd never thought… never considered how much of it Mabel had noticed, how much she'd been aware - Kit had been too little of course - he'd just… never thought.

Of course she had known… and the memory of Robert's coldness towards his daughters made Matthew shiver now. He licked his lips and answered carefully. "Darling they still loved each other very much, you know. Just because… Well, even when you love somebody very much they can still upset you, and you can still fall out a little bit."

"Like me and Bobby? He takes my toys sometimes -"

"Yes, darling, just like that. You know how much Mama and I love each other, but sometimes - we make each other cross. And we get upset and fight a little but - we still love each other very, very much. That never changes."

"Oh." Mabel sniffed, and scrubbed a hand over her face, leaving a little trail of dust from her palm, which Matthew wiped affectionately off. "But - but falling out is horrible!"

"I know it is. That's why we must be kind to each other - and thoughtful, and not only want your own way all the time - like we've told you, remember? Then we needn't fall out much."

"Oh. Do… do you and Mama really fall out sometimes?"

Suddenly Mabel looked at him as if this was the most important question in the world, her eyes wide as she blinked again. "Did - did she and Grandpapa really - really fall out?"

"Mama and I do sometimes, yes, but not very often at all. And it's always over such silly things. And it's never for very long, darling, and it's just as quickly forgotten!" If only it had been so quickly forgotten between them and Robert, but… oh, that was all in the past now. Such a long time in the past. He sighed. "Mama and - her Papa did fall out, too, but - darling, like I said, it didn't ever change that they loved each other. Alright?"

"Mm…" She nodded, but her lip wobbled as though she were about to cry. Isis whimpered a little and nuzzled under Mabel's hand, and suddenly she burst into a huge sob and curled herself tightly into Matthew's chest. Isis whined a little louder, shuffling closer and trying to nuzzle at the back of Mabel's neck as Matthew's arms came tightly about her, rocking and shushing, tugging her riding hat off gently and whispering softly into her hair.

"Shh, darling - what is it? Oh, my little darling… There… Take that - there, dry your eyes - good girl. Shh…" He dabbed at her tearful cheeks with his handkerchief, swallowing past the sharp lump in his own throat at the sound of his little girl crying. How he hated it! He hugged her closer, resting his cheek atop her golden head. "What's brought this on, my darling girl, hmm?"

She sobbed against his chest, her tears staining his jacket.

"Papa - oh, Papa! Please - please don't ever fall out with me - even if you still loved me the most in the world I couldn't bear it! Please promise you won't -" Her words hiccuped out between sobs, and Matthew clutched her tightly, pressing soft, insistent kisses to the top of her head.

"Oh, Bel," he whispered fiercely. If there was one thing he was sure of, it was this. "I will never… never, fall out with you. Not - like that. Not properly. Darling, I promise, I might - get a little cross sometimes, if you've been very naughty but - you know that!" He would never behave towards her as Robert had to Mary, or Sybil. Never. The very thought still angered him, the memory rearing uncomfortably. "Never, do you understand? Look at me, darling -"

Mabel sniffed tearfully, blinking her heavy eyelashes at him as she felt his strong, reassuring hands either side of her face, his thumbs drying her tears.

"Promise, Papa?" she whimpered quietly, searching his face for sincerity and finding it absolutely.

"Promise."

They frowned at each other deeply for several moment, Matthew's expression only relaxing to a gentle smile once Mabel had nodded a little.

"Alright," she sniffed.

"Alright," he smiled, and kissed her forehead, chuckling as Isis's tail started to wag lazily on the floor beside them. "That is… as long as you don't ever give me reason to!" He was teasing, she knew it by the cheeky grin on his face and the sparkle in his eye and the way he leaned forwards and bumped his nose to hers.

"Oh, Papa!" she half laughed, half sobbed, and smacked him squarely in the chest.

"Ouch!" he whined, looking desperately hurt. "That's what Mama does too when she's cross with me." Mabel only laughed at the way he pouted. He smiled. "See? And now we're friends again."

"Yes, Papa, alright," she giggled, and curled up (more happily, this time) against his chest once more, tucking her head under his chin as his arms came around her.

"We'd better go in in a moment," he murmured. "You need a bath, my little darling. And Mama will be cross with me if you don't get it in time for dinner."

"Suppose," she mumbled.

But neither one made any effort to move.

Fin

A/N: Thanks ever so much for reading :) I'm sure there'll be more little vignettes from the ATiL universe to come because I just love the children far too much! I'd love to know what you thought - thank you!