Everyone knew about Harry Potter's scar. It was impossible not to know.
His name was synonymous with the mark. For most people, saying his name called up an image of the scar before what he actually looked like. The scar was the first thing people looked at when they saw him. Their eyes would flicker to his hairline first, before even meeting his eyes or saying hello, as if to make sure it was really Harry Potter.
For the wizarding world it defined him. It told his story before he opened his mouth. It made people think that they knew everything about him just by looking at the strange marking, and Hermione knew that he hated it with a fiery passion.
She also knew that the scar was horribly ticklish.
She discovered the dirty little secret one night after they'd fallen asleep in their secret spot in the library. Hermione moved to kiss him gently on the forehead, and was surprised when he snorted in his sleep, lips curling up into a smile.
She grinned evily and pressed her lips to it again, rubbing the rough skin with her mouth. Harry shot awake, gasping and swatting at her.
"Don't do that again," he'd warned, with a glare that would make Salazar Slytherin feel warm and fuzzy inside.
"You're ticklish!" she laughed, delighted.
"Slytherin's aren't ticklish! I'M not ticklish! Don't do it again!"
It became her favorite way to torture him- peppering the lightning bolt scar with light, furious kisses until there were tears in his eyes and he was choking on his laughter.