You'd think these two dummies with matching holding area, 4 letter names would get along just fine, but the two are said to be battling it out on the set of Tree of Life.

Tensions are running high on the set of Tree of Life. Brad Pitt, who took over Heath Ledger’s role in the adventure film after Heath’s death, is butting heads with co-star Sean Penn, 47. “They’re far from friends,” says an insider close to Brad, 44. “Sean is a bossy kind of guy, and that’s just not Brad’s style. He’s mellower. So spending time together has been a big challenge.”

Thankfully, they don’t have many scenes with each other. “A big theme in the movie is man alone in nature,” notes the insider. “It’s not really a buddy film, and that’s probably for the best.” Their personality clash isn’t the only issue. “Sean is friends with Jennifer Aniston,” says the insider. “Her short film in 2006, Room 10, starred Sean’s wife, Robin Wright Penn. They attended the premiere, cheering Jen on.”

So don’t look for the Hollywood heavyweights to be making too many personal appearances together when Tree of Life hits theaters next year. “Brad hasn’t gone out of his way to praise Sean since filming started,” says the insider, “and that speaks volumes.”

I'm sure it comes down to Angelina. She's probably sleeping with Sean and will have him covered in tattoos and adopting 10 kids in no time. Oh yeah, she's pregnant... hummm.

[source: Life&Style]