Brotherhood star Jason Isaacs gets special permission to guest on HBO's Entourage

So it’s like this: Usually, the folks in charge at Showtime don’t like to lend their actors out to rival networks such as the “It’s Not TV” folks down the way. They’ll nab former HBOers for their original series (See Michael C. Hall, Tracey Ullman), but would rather not go the other way.

With that in mind it’s a pretty big deal that Jason Isaacs, aka Brotherhood’s Michael Caffee, brokered an exception to guest star on Entourage when the HBO series returns in September. Isaacs apparently is a huge fan and couldn’t help being starstruck when he hung out with the Entourage cast.

As for his role — no details ’cause he’s been sworn to secrecy. “I can only say I am not playing myself,” he told EW’s Hollywood Insider blog. “Christ, I hope no one thinks it’s me. It’s quite a character. I wouldn’t want people thinking he’s based on my personality!”

Brotherhood’s currently filming season 3 in Rhode Island. Isaacs will also reprise his role as creepy wizard aristocrat Lucius Malfoy in the next two Harry Potter movies.