John smiles at that, broad and playful, because it's an easy reference to place even without Ianto's internal dialogue.

"Well then it's a good thing you're coming to Neverland with me," he says, "so we can both stay young forever."

He grabs Ianto and turns him in a quick twirl, as if they're dancing -- or perhaps flying? Either way he stumbles a half step at the end and laughs, an obnoxious, low, dirty old man chuckle. Ianto is coming with him to Neverland and John wouldn't have it any other way, because Neverland is boring without friends to hang out with.