She likes to wear them

Fei Wu, AKA, Ladydragon, the current guardian of the Prodigious, was visiting her friend in Paris, Marinette. While they initially bonded over being superheroes, as Marinette was also the superhero Ladybug, they also soon found they enjoyed a similar method of relaxation.

Currently, Fei and Marinette were sitting on the floor of the latter's room, wearing noting but t-shirts and thick diapers. Both had a lot of responsibilities, and Marinette introduced Fei to ABDL as a way to cope with stress.

Right now, they were playing with some babyish toys when they saw someone come in. Thankfully, they already knew their shared secret.