A/N : It's my first story, hope you like it! Not sure whether to write any follow-ups, please tell me in the comments! I do not own Sherlock or any of the characters.
Sherlock is four when he first finds Peter Pan among his brother's old books. He's instantly hooked by the boy who wants never to grow up, by beautiful Wendy and jealous Tinkerbell, and most of all by the pirates. Mycroft is forced to play Peter Pan with him as often as possible, the two of them taking turns playing Peter and Captain Hook, and Sherlock can't decide whether it's more fun being on the good side or the bad.
He's immersed in these games, in pretending he's magical and needed and loved by everyone, and when Mycroft refuses to play anymore he wants to cry because now there's no one but Sherlock, alone in all his incarnations. He pretends and pretends just to keep the years going by, imagines that he himself isn't getting older, without realising that he grows up a little inside himself every time he's called a freak. It isn't the same on his own, though, and it's no surprise to anyone that he's turned to drugs by the time he's fifteen. When he looks around he can see everything in the too-bright Prisma Colour of Neverland, glimmers of fairy dust beautifying the world.
It takes him years before he decides that he's Peter and not Captain Hook, but even then Sherlock thinks that playing the villain is much more exciting. Sherlock Holmes, Consulting Detective isn't someone he decides to be, just who he becomes, and he finally finds his Lost Boys, Lestrade and Molly and Mrs. Hudson. He still slips into being Peter, especially at crime scenes, and Sherlock's occasionally shocked to find that he's not young and invincible.
He doesn't think he wants a Wendy until he meets John Watson and he suddenly realises how lonely Peter has been. Sherlock might always be the centre of attention, but John becomes someone he trusts and cares for more than he thought possible. He can feel Peter falling for Wendy, which he tells himself doesn't mean Sherlock loves John. His blogger is patient and kind and plays pirates with him, and Sherlock imagines that their fairy tale can be perfect.
Then Moriarty starts coming after Sherlock and everything changes. Suddenly he is afraid not of growing up, but of the tick-tick-tick counting down his life that follows him wherever he goes. Sherlock calls Moriarty onto the rooftop because Peter would have survived walking the plank. "Don't forget me." he murmurs on the phone, an old dance, and when John hesitantly answers "Me? Never" he throws himself off the building and pretends he is flying to the second star on the right and straight on 'till morning. He doesn't think this will affect his Wendy; at the end of the story, John grows up and Sherlock doesn't. The end.
But John doesn't move on, and Sherlock wonders if Wendy dreams of Peter and the day he'll come back for her and take her to Neverland. If in another ending of the story, Peter and Wendy might grow up together.
It takes three years but finally Sherlock defeats all of the pirates and finally he can return. He takes a deep breath because John is going to be angry and disbelieving and then he pushes open the door of John's bedroom, imagining he is flying back to a still-open window.
"John… Do you believe in fairies?"