AN: Part 23 of my advent calendar :)
"Papa, what are you getting Dad for Christmas?"
Sherlock looked up from the content in the Petri dishes he was currently examining.
"I'm not telling you, nosy," Sherlock said with a smile, ruffling Hamish's hair.
"Because I think you should give him something very romantic and personal."
"Oh, that's what you think? Well, I suppose I could do that. Have you got any ideas?"
Hamish thought about that.
"Is there anything you're really good at, something Dad enjoys?"
Sherlock cleared his throat. "Playing the violin, I guess," he answered after a second or two of Hamish just looking at him expectantly.
"That's nice!" Hamish clapped his hands together excitedly. "Maybe you could compose something and I can write a song to it, and we can perform it on Christmas Eve!"
"That's a very nice idea." Sherlock smiled at his son.
John usually was better at parenting, and while Sherlock loved Hamish, it wasn't as easy for him to spend time together without one of them getting bored after a while.
John always assured Sherlock that the older Hamish would get, the more interested he would be in the things Sherlock liked.
"Want to help me composing? You can listen to me play and tell me when it sounds like Dad."
Hamish nodded enthusiastically. This was a chance for them to bond.