HOLLYWOOD — After collaborating on some of the most popular and distinctive films of the past two decades, Tim Burton and Johnny Depp are celebrating a special milestone: 20 years together. Next month they'll be on the big screen once again with their seventh film, a new take on "Alice in Wonderland." But aside from the obvious — they're friends, fans love them, etc. — we has to ask: What is the process that keeps bringing these two talents together?

"I think we always treat each thing as what the project is," Tim Burton explained, insisting that it isn't simply automatic that any movie he makes star Depp (even though the last four have). "[Whether I cast Johnny depends on] what the character is."

To us normal folk, it seems like a no-brainer that if you could choose who to work alongside, you'd fill the ranks with your friends. But Burton said that whenever he brings a project to Depp, he wouldn't be offended if Johnny said no.

"[Just] because you know somebody ... [we don't make movies] just to work with each other, but it has always been great," the filmmaker said of their solid track record on everything from "Edward Scissorhands" to "Ed Wood" to "Charlie and the Chocolate Factory" and others. "You want to make sure each thing is on the same level, or better. We always just treat it as what the project is — no pressure either way."

Then there's the matter of who Depp will play. In some movies like "Chocolate Factory," his casting was fairly obvious — but in Lewis Carroll's original "Wonderland" tales, The Mad Hatter hardly possessed the most screen time.

"To be honest, when he called I didn't know what character he wanted me to be," Depp admitted of the duo's initial "Wonderland" conversations. "For all I knew, I could have been Alice — which would have been fine also."

"You would have liked that," Burton teased.

"I was just prepared to do whatever he wanted, whatever character it was," Depp said of their recurring collaborative efforts and what keeps bringing them both back. "Each time out of the gate with Tim, you just try something a little different. You try something and try to keep him interested. You want to try to stimulate the atmosphere."

"Which is great, because that's what movies are all about," Burton explained. "It's fun and interesting to see how his character develops [as we shoot a movie]. How it feeds off of me and the rest of the crew. It's why you like to make movies."

Check out everything we've got on "Alice In Wonderland."

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