Task: Question Answering
Input (English): Passage: The My Scene girls are attending high school in Manhattan when they find out there's a new teen spy movie called "Spy Society" being filmed there, starring Lindsay Lohan (who plays Mariel St. Clair, the lead character) and fictional character Ryan Ridley (who plays Lohan's love interest in the movie). While the girls, Barbie, Chelsea, Madison, Nolee, and Delancey, go to watch it being filmed, they get the idea to sneak into the film by pretending to be extras.
While working as extras for the movie, the girls quickly learn that there's actually a lot of work that goes into making a movie, such as getting to the set really early in the morning, doing hours and hours of takes on a scene, and Chelsea keeps getting terrible roles such as towel girl, trash girl and even being forced to clean up after the horses that are being used in the movie. The girls imagine themselves becoming best friends with Lindsay Lohan, who turns out to be really nice and down-to-earth (and who they do end up becoming friends with).
When one of the actresses on the set gets hurt and is unable to play her part, Madison's called in to take her place. The actress she's replacing plays the movie's lead female villain, although the character only has five speaking lines
After a while, the fame starts going to Madison's head. She also thinks that she and Ryan are dating as they always go out together and the tabloids refer to as "Ryan's Mystery Girl." When she gets invited to a party with Ryan and Lindsay, her friends show up to surprise her. But Madison's very rude to them and pretends that she does not know them. She starts acting and dressing like a diva, and avoid her lifelong friends. This causes her friends to become mad at her and start avoiding her. 
Question: Who starts acting and dressing like a diva?
Output (English): Madison.