"Avengers": Joss Whedon talks sequel, "Buffy" and "X-Men" parallels Joss Whedon, shown in April. This story contains spoilers about "The Avengers." "The Avengers" passed the $1-billion mark in worldwide ticket sales this weekend, and a sequel is already in the works. Does that mean writer-director Joss Whedon will be back at the helm of the franchise that unites Marvel's box-office heavyweights, including Iron Man, Captain America, Thor and the Hulk? "You know, I'm very torn," Whedon said in a sit-down interview in Beverly Hills before the film's U.S. opening. It's an enormous amount of work telling what is ultimately somebody else's story, even though I feel like I did get to put myself into it. But at the same time, I have a bunch of ideas, and they all seem really cool. Whether he gets his hands on the sequel, Whedon's fingerprints are all over "The Avengers," which echoes some tropes found in his other work in comics and television. For one, Mark Ruffalo's much-praised performance as Bruce Banner and his raging alter-ego the Hulk parallels Seth Green's Oz, the werewolf character in Whedon's "Buffy the Vampire Slayer." Like Banner, Oz tries to run from the beast within, isolating himself in far-flung lands while he learns to master his inner monster. Ultimately, Oz learns to accept the wolf and displays Zen-like (though imperfect) mastery over his full-moon manifestations. Similarly, Banner learns to master the Hulk only by accepting and eventually embracing the anger that incites "the other guy." Seth Green as Oz in "Buffy the Vampire Slayer," left, and Mark Ruffalo as Bruce Banner in "The Avengers." Fox / Marvel "I hadn't really connected those," Whedon said, when asked about the Oz-Hulk parallel. But the Oz thing for me was kind of an intellectual exercise. And for Bruce, for me, it felt like a new truth - even though it really is similar and therefore isn't new at all - because Mark and I had spent so much time talking about the way anger manifests. And I've even talked about the Hulk as a werewolf. As much as he's a superhero, he's that type of monster. Whedon's "Astonishing X-Men" run featured young heroine Kitty Pryde. Fans of Whedon's work in comics also may have noticed similarities between Tony Stark's "sacrifice play," saving the world from a nuclear missile at the end of the film, and Kitty Pryde's act of self-sacrifice when she saved the world from a giant missile-bullet in "Astonishing X-Men." "I was afraid you were going to mention "Superman," the first movie," Whedon said. I had never thought about that, since she's more inside [the bullet], but there is a little bit of that. But the ultimate sacrifice and the ultimate threat, when you mix "em up, usually somebody's trying to divert a rocket." Whedon said any parallels between his previous work and the characters and plot in "The Avengers" are unintentional. "I'm not going to do the same thing on purpose; I'm going to do the same thing because I'm creatively bereft, and I've run out of ideas," he joked. Awkward... But one trademark characteristic Whedon embraces in his work is his ability to unite groups of raggedy misfits against imminent evil. Led by anti-hero Capt. Malcolm Reynolds (Nathan Fillion), "Firefly's" crew of lost space-wanderers exposed the misdoings of an interplanetary government that stepped out of line. A teenage girl and her "Scooby gang" of freaks and geeks saved Sunnydale and Earth from demons and demented gods in "Buffy the Vampire Slayer." And now, in "The Avengers," disparate superheroes worked through their egos and hangups, pulling together as a team to defend the planet against alien invaders. So which misfit crew is Whedon's favorite? "You know, I love all my raggedy children," he said. But if I could be anywhere, I'd be on board Serenity. Mark Ruffalo says the Hulk has "found his family" "Avengers": Cobie Smulders up for sequel duty "Avengers" set visit: Whedon's heroes and humor