EXCLUSIVE! Meet Scout Taylor-Compton, Kristen Stewart's BFF — AND Her Biggest Competition!

Although she may have lost roles to Kristen in the past, Scout tells us that the situation is often reversed – and K-Stew lost the lead in Halloween to her!

Believe it or not, Kristen Stewart wasn’t always the hot commodity she is today. In fact, she’s lost out on many a role to BFF Scout Taylor-Compton!

Although Scout lost the lead in the 2007 horror flick The Messengers to K-Stew, the tables HAVE turned. “We go up against each other a lot,” the 21-year-old actress told HollywoodLife.com exclusively at K-Swiss’ Players Series dinner party in Venice, Calif. Sept. 20. “We’re very similar to each other. She went out for Halloween and I got that. It’s really great that we are really good friends, but we do take each other’s roles. It’s kind of like ‘Congratulations! We can separate being friends from business.'” She added sagely, “You can be friends or enemies. I choose to be friends – I don’t have enemies.”

If you think Scout sounds harsh, don’t believe it for a second — she’s just wise to the Hollywood game. In fact, she and Kristen, 20, have actually joined forces in the past to co-star in The Runaways; Scout played rocker Lita Ford to Kristen’s Joan Jett. So how, exactly, do the girls manage to maintain their close friendship? “We’re very similar,” Scout said. “We’re very laid back. We’re not high-maintenance people. We’ve true to ourselves.”

This much is fact. Although she was deep in the throes of promoting the Twilight Saga: Eclipse back in June, Kristen still managed to find the time to represent her pal at the LA premiere of Scout’s indie flick, Love Ranch.

Another factor that helps their friendship is a mutual love of music. “I’m starting a band,” Scout revealed. “I play the drums. [For The Runaways] I had to learn guitar, so I also play guitar now.” Sadly, HollywoodLifers, life will not imitate art for Kristen and Scout. “We did a lot of [jamming] together in The Runaways; we had rehearsal all the time,” she said, adding, “I do know that Kris still plays, but no, we don’t jam together.”

SAD!