А white picket fence and two point five kids

When they had first brought Kitty home, Sherlock had made the very convincing argument that she didn’t even have object permanence yet, so so what if they kept doing the crime wall thing in the living room? It wasn’t as if she’d remember it, or that it would permanently mentally scar her.

And so it had been a gradual thing. Ageing and growing and developing is such a slow process that by the time Kitty reached out to the crime wall and slapped clumsily at a picture of a beaten bloody corpse and giggled around the word “mallet” she was four years old and it was already far too late. And she’d also just correctly identified what weapon had been used to kill Rebecca Bunch.