A/N: This is my parent!fic for the trope bingo challenge for Let's Write Sherlock!, on card two. The title may change since I'm not completely happy with it.
It was supposed to be simple. It was Greg's two weeks with his daughter, and there was a carnival that weekend. Emily wanted to go, and Greg didn't mind taking her (he enjoyed playing the games as much as Emily did sometimes), so they made plans to go on the last day, which was Sunday.
Mycroft had managed to clear his schedule so that he could accompany them, not seeing the point of going to a carnival but accepting Greg's suggestion that it would be a good time to bond with Emily. It sounded like the perfect plan, and he would actually admit (to Greg if no one else) to looking forward to it.
So, when he arrived at Greg's flat to find a despondent Emily sitting on the sofa while Greg rushed around putting on his work clothes and trying to find someone to watch Emily, he volunteered to watch Emily for the day.
Greg was relieved, of course, and after making sure that Emily was alright with the arrangement he headed in to work. Mycroft was left alone in the Lestrades' flat with a child he barely knew and had met only briefly before.
Mycroft had never had anything to do with children in his adult life. He had assisted his parents in caring for Sherlock, of course, but he was only seven when Sherlock was born and his parents did the majority of caring for them both. He knew that he was only watching Emily for the day, for a few hours most likely, but he also wasn't naive enough to believe that this would be the last time he was left in charge of Emily. If he and Greg did move forward with their relationship (which was progressing nicely, in his opinion, albeit slowly because of their time consuming jobs), then he would eventually be a second father to Emily and today could very well determine whether or not that would work.
While he was trying to decide what to do, he noticed that Emily was still downcast, upset not only that she wouldn't be able to spend the day with her father like they planned (something she was used to but was still upsetting), but that she would miss out on the carnival, something she had been looking forward to for several days.
That was how Mycroft Holmes ended up escorting his partner's daughter to the carnival on his own.
He was grateful that Emily seemed to be well behaved compared to the other children. She stayed beside him as they entered the fairgrounds, holding onto his hand but not trying to drag him anywhere. She was a quiet girl, something he thought she had inherited from her father, and she was shy in the presence of an almost stranger in the beginning. She quickly warmed up to him, however (surprising Mycroft greatly, as he had never been good with children), and was soon chattering away about how to play all of the different games.
Most of the day passed in a blur, wandering through the crowd of people, being directed by the small girl clutching his hand. There was a dart game that she was surprisingly good at, winning a stuffed fox that she hugged to her chest. She tried and failed to win a fish by throwing ping pong balls into small fishbowls, and Mycroft couldn't help himself but try as well. It took several tries (and Emily had been sworn to secrecy about precisely how many tries it had took), but in the end the girl looked so happy that he thought it was worth the aggravation of the game if the outcome made her that happy.
They left not long after that, Emily wanting to take her new pet home and add it to the fish tank in her room at Greg's flat. She admitted, quietly, that every time they went to the carnival together, her father would win her another fish, as he was very good at that game.
They stopped for Chinese, taking it back to the flat with them and eating after Emily got her new fish settled. Mycroft realized, watching her laugh at something in the film she had put on for them to watch, that he was enjoying himself far more than he had anticipated.
Soon enough, it was time for Emily to be in bed, and the little girl went back to her room to get ready for bed and go through her nightly routine, assuring Mycroft that she didn't need any help. He received a text from Greg while she was in the bathroom, saying that he should be home about an hour after Emily went to bed and apologizing for needing to abandon them both earlier.
Emily came back while Mycroft was composing his reply, setting the stuffed fox she had won in his lap and hugging him quickly before heading off to bed. Mycroft looked down at the toy before looking over at Emily's door, a small, fond smile making its way onto his face. He sent his text to Greg, omitting many of the details of the day. After all, it wouldn't do to have anyone think he was going soft.
Greg found out anyway, the next morning when he asked Emily what she and Mycroft had done on their day together.
(Mycroft kept the stuffed fox, putting it on one of his many bookshelves in his house. It stayed there for many years, until Emily was grown and had a child of her own, then he gave it to the bright eyed little girl, already foreseeing another trip to the carnival in his future.)
