Emma Watson is reportedly dating her 'The Perks of Being a Wallflower' co-star Johnny Simmon.

The 21-year-old actress - who shot to fame playing Hermione Granger in the 'Harry Potter' films - is said to have fallen for the 24-year-old actor on the set of the drama movie, which is being shot in Pittsburgh, Pennsylvania, and the pair are already very close.

A source said told HollywoodLife.com: "Emma and Johnny met shooting 'The Perks of Being a Wallflower' and have gotten serious fast. She loves how down to earth and normal he is and thinks he's the nicest guy. He feels the same way about her. She doesn't act like she's one of the biggest stars in the world."

Although the relationship is still in its early stages, the pair are said to have become virtually inseparable

A second source said: "They have really fallen for one another and both aren't dating anyone else. She once said she'd never move to LA, but I think she's reconsidering ... especially because Johnny lives in Los Angeles."

Emma previously dated financier Jay Barrymore but their two-year relationship ended in March 2010 after two years.