She's a bedwetter

Alya Cesaire was sitting down to watch a movie with her best friend, Marinette Dupain-Cheng. It was the first sleepover the two had together, and they were having a lot of fun, playing games, eating junk food, and trading secrets. One of the last things they were going to do was watch the newest Ladybug movie on Alya's streaming service before the two headed to bed for the night.

Before Alya could press play, her older sister, Nora, blocked the TV. "Alya, it's getting late. You know the rules." She said, making Alya blush a little.

"N-Nora, can't this wait?" Alya asked nervously, confusing Marinette.

Nora firmly shook her head. "You remember what happened the last time you sat down to watch a movie and accidentally fell asleep?"

Marinette had no idea what was going on. "Uh, what happened?" She asked.

"You seriously haven't told your friend yet, sis?" Nora was surprised Marinette was out of the loop here.

"Told me what?"

In response to Marinette's question, Nora ignored Alya's protests and held up a thick diaper that looked like it was in Alya's size. "She needs to wear these at night or else she'll go all over the sheets."