Firefly

LOS ANGELES (Zap2it.com) - Capt. Tightpants strikes back.

Nathan Fillion, who stars as Capt. Malcolm "Mal" Reynolds in Universal’s upcoming "Serenity" movie, is giddy as a schoolboy at the Wizard World convention in Long Beach, Calif., on Sunday, March 20.

During one portion of the Q&A — in which he participates with director Joss Whedon and actors Ron Glass, Sean Maher, Jewel Staite and Morena Baccarin — he discusses nicknames the cast members gave each other.

"In case you don’t ask, we forgot the best one. So, please put this on the Internet," he says, referring to earlier reports circulating online that he was dubbed "Capt. Tightpants" by his co-stars. "We call [Sean] — because of one of the lovely scenes he did in ’Serenity’ — Sean ’The Bod’ Maher."

Maher, who plays Dr. Simon Tam in the film, is only slightly embarrassed, but not surprised. After all, Whedon and the cast have been ribbing each other in cruel, but good-natured fashion during the entire event. Earlier, Maher had taken his own pot shot at Fillion, saying that reuniting to film "Serenity" — the big-screen successor to Whedon’s sci-fi series "Firefly" — was like returning to school from summer vacation, except "Nathan still sucks, but ... "

"What can you do?" finishes Staite, who plays mechanic Kaylee Frye.

Fillion is obviously the troublemaker of the group: egging the audience for more applause, twitting his co-stars, breaking the arm off an action figure, "revealing" false spoilers and drawing Whedon’s wrath by tipping over the director’s name placard.

Whedon, who’s more of a cool uncle than a patriarchal director, does little to maintain order. He dishes out his own insults, referring to Fillion as "what’s his name" and "the least talented" cast member. At one point, he even pretends to angrily strangle the star.

Despite the shenanigans, Whedon proves that he can be protective of his actors when a fan gets out of line and asks Baccarin, who plays a courtesan in the film, if she performs at bachelor parties.

After the audience gasps and Baccarin replies that she’s "a little offended," Whedon tosses back, "Don’t talk to my cast that way." After a pause, in which he tries to remember the first, unrelated part of the question, he apologizes jokingly, "[Sorry], I was consumed by rage."

"Serenity" originated with "Firefly," the short-lived science fiction/western series that FOX canceled after airing only 11 episodes. The film is set 500 years in the future and centers on the transport ship Serenity manned by a band of law-bending misfits. When the crew takes on two fugitives, they find they’re being pursued by the military as well as the cannibalistic Reavers.

"Serenity" flies into theaters Sept. 30.