It's a side effect of a lost Miraculous

Sabrina Raincomprix was happy to take a strange necklace from her "best friend", Chloe Bourgeois. Sure, Chloe said she "didn't want something that ugly", but she still trusted Sabrina with this pretty necklace.

One night, Sabrina was trying the necklace on, when a strange being energed from a ball of light coming from said necklace. It reminded her of that little dog thing she met before becoming Miss Tracker.

"A-Are you a Kwami?" Sabrina asked nervously.

The being in question, a bird-like fairy, nodded in agreement. "I sure am. I've been waiting forever to find someone to awaken the Stork Miraculous. You can call me Wingg, baby girl."

"Wait, baby girl? What do you mean?" Sabrina asked.

Wingg chuckled at the girl's naivete. "Don't you know the person who is able to awajen the Stork Miraculous is one who is young at heart and has hidden desires of youth?"

Before Sabrina could ask anything else, she felt her panties growing thicker. She gasped as she looked underneath her skirt and saw a thick diaper with baby block prints on the front. "What did you do to me?" She hissed.