Words can't even begin to describe how much fun it was to write "Briar Nose". First, I have to thank Nimori, for writing the challenge in such a way to suggest a very light-hearted tone -- and you'll notice I almost used her words literally when Harry finds the "maiden". I also have to thank my beta Kate for the title, which is a play on "Briar Rose," the title of the Brothers Grimm version of the Sleeping Beauty legend.
What I enjoyed was taking two different texts -- the Potter books and the Sleeping Beauty fairy tale -- and trying to combine them in a reasonable way. (If you haven't read fairy tales recently, you can read the Brothers Grimm version online .) Any time you try to mesh two things, little details have to give, and figuring out what would give where was a lot of fun.
For example: in the fairy tale, at her birth the princess is cursed by the uninvited wise woman (wicked fairy godmother, in some versions) to prick her finger on a spindle. In my story, Severus is cursed to prick his finger because he won't join Voldemort, but I still have the "uninvited wicked fairy" play a role by cursing Harry -- and that fulfills the Potter books plot of Voldemort trying to kill Harry and ending up getting (temporarily) vanquished. I couldn't imagine Severus spinning flax, so he gets pricked by a potions ingredient -- and the obvious choice was the thorn of the rose that grows around the castle in the fairy tale.
So, essentially, every time a parallel fails in one story, it's to fulfill a condition from the other story. (Except when I'm trying to be clever on my own!) To make up for parallels that *have* to fail (for example, Severus can't possibly be Harry's teacher), I tried to bring in other details from the stories to convincingly set the characters (in this case, having Severus deliver a version of the "brew glory" speech). I couldn't come up with any plausible way to have Peter betray James, but I could still make him a betrayer.
I also tried to write the story not just in fairy-tale style, but in the style of a fairy tale that *knows* it's a fairy tale -- think Princess Bride. This let me do all sorts of cute little asides from the storyteller to the listener, so I could make the 18 year span of my story grow into the 100 years of the fairy tale (not to mention give Severus a makeover as a beautiful maiden!) When I saw that the tale would be exaggerated in the telling, I knew immediately it had to be Hagrid who told it, and of course a giant fits well into a fairy tale.
Finally, I delighted in throwing in little bits and pieces of canon reference in unexpected ways. You probably noticed how I made Harry a "Seeker" -- did you catch that James was a Chaser? And you might want to try rearranging the letters in Lily's father's (full) name.