Emma Watson's step-brother helped her through her first heartbreak.

The actress plays Sam in The Perks of Being a Wallflower, with Ezra Miller portraying Sam's step-brother Patrick. The two are very close and their friendship got Emma thinking about her own upbringing.

"My relationship with Ezra really reminds me of my relationship with one of my step-brothers David. We really relied on each other throughout that experience [of growing up] and confided in each other a lot," she told UK TV show Lorraine. "Because it's a time of so many firsts the first time you get your heart broken, it's quite a shock and you don't know if you're ever going to recover and it's never happened before. Those people who help you through experiences are really key."

Sam and Ezra take a new student called Charlie under their wing in the movie. They are both flamboyant and in one scene perform a crazy dance at a school event.

Emma was determined to get the choreography right when she heard about the scene.

"Ezra and I were like, Right, this has got to be the best dance ever.' And we watched back a load of films, we wanted to sort of steal the best moments from all the best dance films. So we have the Dirty Dancing lift, and the Grease where she slaps him around the face,"