Amnesia [MARICHAT] ON HIATUS
When Marinette gets hit by a car while crossing the street on her way to school, she ends up losing all of her memories of who she was - including Ladybug. She's scared and lost, and everyone is a stranger.
Just when she starts to get to know Chat Noir and to understand herself as Ladybug, her memories vanish again.
Chat Noir is the only one who can save her.
Okay, I don't own Miraculous Ladybug, obviously, or their identities would have been revealed already and Luka would be way more involved (I love Luka).