Mariah didn't know that her mother had annoyed a Faerie princess. The Faerie Lord sent to retrieve her didn't want to do the job. When you're immortal, twenty years is just a bit of procrastination.
Kidnapped twenty years late, Mariah is trapped in a magical garden by faeries that are clueless about humans. The Queen says she's a baby, so they take Her Majesty's word for it.
Meanwhile, the faerie that took Mariah's place is determined to play the part of a baby, at least as well as she understands it.
They both need to get home, but until then, they're babies out of place.
Content Warning: Forced Diapering