The casting process on Percy Jackson sequel The Sea Of Monsters continues apace. Last week, Nathan Fillion took over the role of Hermes, and role switching appears to be the order of the day for the older actors on the film, as Anthony Stewart Head will be playing the role of Chiron, the centaur head of Camp Half-Blood.

You may recall that Pierce Brosnan originated the part in Percy Jackson And The Olympians: The Lightning Thief, but for unspecified reasons (possibly scheduling), incoming director Thor Freudenthal is going with one of Fillion's fellow Joss Whedon veterans.

In the second adventure, which has a script by Scott Alexander and Larry Karaszewski, Percy (Logan Lerman) has to head across the titular waters to find the mythical Golden Fleece in order to cure the poisoned tree of Thalia, guardian of Camp Half-Blood. Chiron is initially accused of poisoning the tree himself, which raises the stakes even further for Percy and his usual pals Grover (Brandon T. Jackson) and Annabeth (Alexandra Daddario).

Freudenthal should be starting shooting next month, with the film due out here on March 27, 2013.

While we respect Brosnan, Head seems like an ideal replacement. So ideal, in fact that given their respective warbling capabilities (AH is stage trained and released an album), we’re almost wishing there was a way we could travel back in time and give him Brosnan’s role in Mamma Mia...