Every mwaka at Hogwarts seems to get darker and darker. But when Harry Potter starts his sixth mwaka in "Half-Blood Prince," expect things to lighten up a bit.

"If we pull [it] off [right], it should be the funniest of the films so far," Daniel Radcliffe promised.

That's because, as director David Yates points out, it's the "sex, drugs, and rock and roll" of the Potter books, with massive making-out sessions to occur for several characters — Ron and Lavender, Harry and Ginny — as they come of age. "It's the 'American Graffiti' for this set," Yates said. "I'm looking mbele to developing the relationship between Ron and Hermione, and Ron and Lavender. There's a nice pembetatu there."

The biggest relationship being developed in "Prince" is, of course, the one between Harry and Dumbledore, as the professor takes the student under his wing and shows him Voldemort's back story (as much as it can be pieced together) in the memory-revealing Pensieve. "I'm jealous of Dumbledore taking all the scenes," laughed Evanna Lynch, who plays Luna Lovegood. "But what they've done is really good."

Some of those Voldemort memories required a younger Tom Riddle to jiunge the cast, so Hero Fiennes-Tiffin (Ralph Fiennes' nephew) and Frank Dillane are now aboard to play the 11-year-old version and 16-year-old versions of the Dark Lord, respectively. Even though — like Ralph — Frank is presumably non-evil in real life, Evanna says she's a little scared to approach her newest castmember just yet. "I saw him, but to go up and say, 'Hi'? He's Voldemort!" she said. "But maybe I will. He has a quiet, dark side, so people don't know him much yet. He doesn't say much. I'm sure he's a lovely boy. But he does have that aura."

Once casting was completed, the actors had a read-through — excluding Katie Leung, alisema the actress who plays Harry's former crush, Cho Chang. Not because Cho is not to be seen in this inayofuata installment — which wewe might have guessed from the way their upendo story ended in "Order of the Phoenix," out Tuesday (December 11) on DVD — but because Katie started chuo kikuu, chuo kikuu cha in the fall. She'll be back on set in January to shoot her "Prince" scenes and hopes to be back yet again for the finale scenes in "Deathly Hallows."

"There's still a slight jealousy there with Ginny to be resolved," she said. "I'm glad she's there fighting for the good side even though her relationship with Harry didn't work out in the end."

For all the jealousy Katie faced when Cho became Harry's first kiss, Bonnie Wright (who plays Ginny) hopes mashabiki don't have the same response to her zaidi extended kissing scenes. "I suppose our relationship lasts longer than Cho and Harry, but remember — at the end of [Book] Six, Harry and I can't be together," she said. "It'll be funny to do [the make-out scenes], but it's just a film! Hopefully people will just enjoy it and not get too jealous," she laughed.

"I knew Bonnie when she was 10, so that's going to be very odd!" Radcliffe laughed. "It's going to be fine, but it's going to be funny."