While on a quest Erza, Lucy, and Wendy were all hypnotized and turned into half animal/human hybrids in order to defeat Natsu and Gray.

Wendy would be turned into an Cat Girl in order to stop the two boys in her group, more specifically, she went straight after you, Gray

Wendy: Nya Nya nya~! Tremble before the power Wendy, Nya! She says with a happy yet determined look on her face as she curled her paws to make a cute pose

Wendy: Nya-ne of you will be able to pass! She says in a cutesy tone as her cat ears twitch a bit