"Don't worry. You're just as sane as I am."
Harry blinked and turned to see that Luna wasn't addressing him this time, but George. George looked even more confused than Harry, but he'd known Luna most of his life so he simply replied. "Uh-huh," and went on staring out the carriage window at the passing scenery.
The carriage was full of 7th and 8th years returning to Hogwarts for the first time since Voldemort's retreat. Hermione had been keen, of course, and Ron had submitted to the combined persuasion of his mother and girlfriend. Neville's Gran had insisted that he get a 'decent' NEWT year and Harry, like George, had been adrift after the war ended so that a year as a schoolboy again had seemed like a haven from too many choices, too much of... everything really.
So here they all were...
"No, really," Luna persisted, touching George gently on his shoulder. "I have an identical twin, too, you know. That's why I know about horcruxes."
The word rang through the carriage like the clanging of a bell. Harry, Ron and Hermione stiffened, and Hermione snapped, "WHO told you that word?!"
Ginny and Neville were looking from the trio to Luna in incomprehension, and even George turned to pay attention, which was unusual for George these days.
Luna's gaze was dreamier than ever as she said, "My mother told me the story when I was little - don't you know it?
"Once upon a time there was a baby waiting to be born and he felt lonely, all there by himself in his mother's body. He wished so hard not to be alone that his magic split him into two identical babies, each with half a soul. When they were born the babies grew even closer but one day there was a terrible accident and one of them died.
"Because the babies shared a soul they were horcruxes for each other, tied beyond the claims of death. As the surviving baby grew older, married and lived a long and happy life, his dead twin was always at his shoulder, sharing his joys and sorrows. And when Death came to claim them he took them both together, hand in hand, for they had been one soul and could never be parted."
George's eyes were filled with tears, and he was not the only one.
"Is that true?" Ginny whispered.
"Oh yes," Luna said. "My twin is always nearby. She's my best friend. I don't usually talk about her though - it makes people uneasy."
George's face was filled with an emotion so strong, so incandescent that it surpassed wonder or joy.
"Fred?" he whispered to the empty air before him. And then he smiled.