Before the vampire Edward Cullen, there was the Hogwarts student Cedric Diggory. British actor Robert Pattinson went from the mega-franchise of "Harry Potter" in 2005's "Goblet of Fire" to the mega-franchise of last year's "Twilight."

Now that Pattinson has entered a world in which bloodsuckers chill Stateside — and now that he must contend with Twilighters going wild for every bit of RPattz gossip out there — Daniel Radcliffe looks at his onetime "Potter" co-star's career arc as educational.

"It's really interesting for me, as somebody who is a central feature of a pretty huge franchise," said Radcliffe, who returns as Harry Potter in the "Half-Blood Prince" on Wednesday (July 15). "It's interesting to watch — because I haven't seen 'Twilight' — and to suddenly be able to just watch another franchise go massive is really interesting."

"Twilight" has given Radcliffe a chance to understand how an everyday fan must react to his own franchise. "I have no concept of what 'Potter' looks like to the rest of the world because I'm so involved in it," he explained. "So to watch 'Twilight' kind of explode globally had been fascinating."

The two British stars, though, haven't connected since they filmed "Goblet of Fire." "People always assume that as a celebrity, I know all the celebrities," Radcliffe laughed. "But I know very few famous people!"

Another of Pattinson's "Potter" co-stars, Emma Watson, always knew Rob had the goods to make it big. But no one could have ever guessed how big he would actually make it. "He was always very intelligent, nice, talented, good-looking, had everything there," she told MTV News. "I'm not surprised he's been successful. I'm surprised that it's got this insane. I think he's a great actor."

Having worked with both Radcliffe and Pattinson, who would Watson say is the most enchanting? "Obviously, I'm going to have to say Daniel, because he's just gorgeous," she said with a smile.

Check out everything we've got on "Harry Potter and the Half-Blood Prince."

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