Secrets and Santas

"You're really doing this?" said Mary, watching Lily attempt to stuff a jar of marmite into her suitcase. / "Yes," said Lily. "It's a perfectly normal thing to do." / "Taking an extra large jar of marmite on holiday with you or posing as James Potter's girlfriend over Christmas?" / Fluffy fakedating!au. Multichapter. What could possibly go wrong?