Had anyone heard of Peter Pan in Scarlet by Geraldine McCaughrean? Its book jacket proclaims it "The first-ever authorized sequel to J. M. Barrie's Peter Pan"; in 2004 the copyright holders of Peter Pan searched for an author to write an official sequel, and McCaughrean got the honor. This is not like the Dave Barry or Ridley Pearson pastiches, nor is it one of those sideways twists on the Peter Pan story; the language is meant to reflect J.M. Barrie's original work, and so is the feel of the fantasy, with sly jokes and nostalgia touches adults will get. (If you haven't read the original Peter Pan and Wendy I recommend you drop what you're doing and have a look now; you won't believe how much of it's aimed at adults.)
I thought this sequel was enchanting. As a sequel it retcons nothing of the original work and yet still manages to slip Wendy and the Lost Boys back into the work neatly. There are 1930s England sensibilities crossed with Neverland familiarities. There's clever child-logic-magic. And there's darkness and heartbreak poking at the edges, too. Very much recommended.