Swapped Lives (Miraculous Ladybug)

Marinette Dupain-Cheng is a model who has boys (and some girls) falling left and right for her. Her mother passed away recently and she was left with her father, who became a workaholic and stopped paying attention to his girl.

Adrien Agrest is a common bakers son. When a new girl shows up at his school, Adrien falls for her. Hard. Marinette is to oblivious to see that though.

When they separately have incounters with Master Fuu, they received their miraculouses. But not thee Miraculous they were supposed to.
Adrien got the Ladybug Miraculous, while Marinette received the Cat Noir Miraculous.

Marinette falls for the boy in red during the first mission, and vows to love whoever is under the mask.