The exception for Halloween isn't written into the Statute of Secrecy, but it might as well be. For three hundred years witches and wizards have been compelled to wear Muggle clothing anywhere they might be seen – every day, and every night, except this one.
"Are you ready yet?"
"Give me ten minutes!" Pansy shouts.
She hears the floorboards creak, and then Luna appears in the doorway.
"You said that fifteen minutes ago," Luna observes calmly. "You look nice."
"I want to look perfect," Pansy says, applying lipstick with precise wand-strokes.
"You already do," says Luna. "Although Hermione told me there are Muggle laws against showing off your underwear in public."
Pansy sticks her tongue out - carefully, to avoid smudging her lipstick - and takes the robe that Luna holds out. It's deep purple, custom-made in wool and silk with luxury charms woven into the cloth.
Pansy slides the robe on, and Luna's hands smooth down her back to straighten the fabric.
"How do I look?"
"The children will say you're too pretty to be a witch," Luna replies.
Pansy smirks. "They say that every year," she says, and reaches to take Luna's hand.