Rose is in the same class as the protagonists Marinette and Adrien. Blond, blue-eyed, and presumably French, she is known for her sweet temperament. Look at the picture at the top there: does she have a finger pressed against her own eyeball?
When her classmates were attempting to make a homemade horror movie, Rose was in charge of the catering. Even when a real monster showed up and started devouring them one by one, she was still making sure that everyone had enough to eat.