Author's Notes: Inspired by a prompt from Tumblr user desperatelyseekingsherlock, who wanted a Sherlolly AU of the 1995 film "The Parent Trap".

Notes, 10/05/2015: Please note that this fic has recently undergone a MAJOR, and well overdue, re-write. The plot is basically the same but what I've done is that I've polished up the writing in some areas, changed the names of the twins to Poppy and Isla, and switched Tom for an OC named Mark (as the Tom shown in s3 was too cute for me to paint as a huge obstacle to the twins' schemes). Other than that, enjoy!

Of course it wasn't meant to last. It had been too much, too young really. Molly sighed and eased the ring from her wedding finger.

"We're not even divorced yet," he said from behind her. "That's a bit pre-emptive, don't you think?"

She turned and against her better judgement, her heart leaped a little. Even the anger she felt at him didn't detract the fact that he was deathly handsome with that smirk on his face. God, but she could fall in love with him all over again. She could.

"Twelve months, I've kept this ring on. I think it's time you got it back," she said, dropping the ring into his open palm. Her fingertips brushed lightly, briefly, against his skin. His fingers scooped up the ring, his eyes skimming over it. He pocketed it and smiled, but it failed to take.

"Very well. I suppose we had best get on with it."

Sherlock sighed and trudged up the stairs to 221b. His bad mood only increased when he saw that Mycroft was sat on the sofa and carefully twirling his umbrella between his fingers as he always did.

"Brother," he grumbled, picking up his violin and sitting in his armchair. There was a moment of silence between the two brothers, where all that could be heard were Sherlock's calloused hands gently picking at the strings of his violin.

"It was quick and painless, I hope."

"You don't hope, Mycroft. You know."

"Indeed I do," he said quietly before directing his gaze towards his brother. "You plan on staying here, I believe. Are you quite sure that's wise, considering?"

"Considering what?"

Mycroft let out a sigh and a small shrug. "Memories. She did live here after all."

"Much to your chagrin," Sherlock said. He couldn't help but smile at the memory a little. On hearing that his young brother had decided to marry, Mycroft's eyebrows had arched upwards and his only remark had been to remind Sherlock how upsetting it would be to their dear Mummy. At the time, Sherlock couldn't have cared one iota about what Mummy thought, or what Mycroft thought either. Of course they'd have disapproved. Whirlwind romance, they'd have termed it. Much too fast.

Now he was sat in 221b Baker Street a divorced man with a three month old lying asleep in his bedroom.

An idle heavy sigh had Sherlock aiming a glare at his brother. Before any snide remark or exchange could be made however, there came the soft sound of a baby cry. Sherlock immediately unfolded himself from the chair and moved towards his bedroom. He heard Mycroft follow suit.

He entered into the bedroom and moved towards the cot by the window. It was an old cot, donated to him—them—by Mrs Hudson (who'd apparently got it from a friend; the details were fuzzy, he hadn't really listened when she'd told him). Inside the cot, swathed in blankets to keep the cold away was his tiny three month old daughter.

Slowly, her eyes opened. On seeing her father, her mouth broke out into a grin and she reached out as far as she could as she quietly babbled out her need for him to hold her. Sherlock was only too happy to oblige. Carefully, he picked her up and supported her in his arms. He couldn't help but smile as she grinned at him.

"I assume you chose not to name her after Mummy," Mycroft said, leaning against the doorway slightly.

"You assume correct. Her name's Poppy, if you really must know," Sherlock said and he finally turned to face his brother. Poppy saw her uncle, whose frown deepened on seeing the child's face.

"Yes. That's your uncle. Mycroft Holmes," he whispered softly. Poppy's grin widened and just as she had done to Sherlock, she reached out to Mycroft. Sherlock stepped forward, but Mycroft's frown deepened in disapproval. Poppy's face crumpled and she whined, reaching out further.

Originally, he took her from Sherlock to prevent her from crying. Sherlock merely stepped back and watched. It only took a few minutes. His brother's expression barely changed but the light in his eyes gave everything away. Eventually, he looked to Sherlock. The frown was back in place.

"I suppose she'll be fine," he said coolly before he handed Poppy back to her father and swept from the flat. Sherlock looked to his daughter, deftly playing with her tiny fingers and stroking at her chubby cheeks.

"See that Poppy? You just melted the iceman."

On the other side of London, at the check-in desk at Heathrow Airport, things were a bit more hectic. With a bulging suitcase at her feet, Molly sighed heavily and scooped her hair into a tight ponytail, smiling for the benefit of her daughter, who was currently lying against her chest, comfortable in the cocoon of the baby carrier as she gurgled a little, the sound something that both warmed and hurt Molly's heart in equal measure. There should've been a second baby there, gurgling along with her sister but it was not to be.

They shouldn't have married. They shouldn't have even considered the idea of children. Yet, in their love-addled minds, they had. It wasn't that she regretted having kids; what she truly regretted was that the baby beside her would never know the mad, eccentric and utterly marvellous man who was her father. Of course, if truth were to be told, it was really the best thing to do. It was better for her daughter not to know her father than to suffer through the effects of witnessing an unhappy marriage. Wasn't it?

She was at the check-in desk before she knew it. The check-in attendant said nothing but just waved her through with a small, sympathetic smile before moving on to the next person in the queue.

Molly walked through the airport, more than a little bit stunned.

This had all happened. It had really happened. She had divorced Sherlock Holmes, and she was now heading towards the flight that would take her from her dear United Kingdom and to Phoenix, Arizona.

It was the right thing to do. She repeated that to herself a number of times, the words a slight breath on her tongue, but when she sat in that seat on the plane, and watched as the plane roared down the runaway and up into the air, there were no amounts of softly spoken words that could stop her crying.