Percy Jackson 2 casts Nathan Fillion and Anthony Stewart Head

Catapulting it into the must-see list of Joss Whedon fans everywhere...
Following swiftly on the heels of Nathan Fillion's casting as the swift-heeled Hermes, Anthony Stewart Head has been cast as Chrion in Percy Jackson and the Olympians: The Sea of Monsters. Yes, the man who played Giles in Buffy the Vampire Slayer and King Uther Pendragon in Merlin is returning to the fantasy genre once again. This makes two Whedonverse actors cast in the movie so far, both in roles recast from the first movie. Nathan Fillion is replacing Dylan Neal, and Anthony Stewart Head is replacing Pierce Brosnan, arguably proving once and for all that Rupert Giles beats James Bond. (By the way, if Judi Dench ever retires from the role: Anthony Stewart Head for M. Just saying.)
Of course, there could be any number of reasons for Percy Jackson 2’s recasting, including scheduling, budget, and cast chemistry. Or maybe the filmmakers are just toying with us. Awesomely. (Maybe halfway through the movie, one of the characters will suddenly transmogrify into the appearance of another actor, like with The Best. Cameo. Ever. in The Muppets.)
However, the simplest explanation for the recasting is simply that there are few actors cooler than Nathan Fillion or Anthony Stewart Head. Of course, they've worked with Joss Whedon, arguably the greatest writer in the business, and so have an inherent advantage. Great writing affords actors the opportunity to really flex their acting muscles. ("There's the deltoids of compassion, the abs of being kind...it's not enough to bash in heads; you've got to bash in minds...")
Maybe people will see the movie, and go ‘Hmm, those actors are good…I wonder if they’re in anything else where they have more screentime? Like, say, a TV series…’ And then they’ll go and watch Buffy and Merlin and Firefly and Castle, and have their minds blown. (And if they’re like ‘Meh’, then the rest of us shall deny we were ever friends with them.)
Seeing as they’ve both played memorable roles in Joss Whedon musicals (Fillion singing ‘Everyone’s a Hero’ as Captain Hammer in Doctor Horrible’s Sing-a-Long Blog, Head singing ‘Standing’ as Giles in the Buffy musical episode ‘Once More, With Feeling’), perhaps they’ll get to sing in this movie (a cheesy duet about sea monsters, or some exposition or other, or anything really—maybe ASH could sing something soulful and eloquent and cultured, and then Fillion could jump in with cheesy, bombastic backing vocals and hilarious facial expressions—perhaps with added air guitar). Filmmakers, please make this happen.
In fact, the movie could even be a musical set in the world of Greek mythology. Like Disney’s Hercules, only better.
In any case, the casting directors should get a raise. And get to cast everything ever (subject to availability – and of course there are other really good casting directors, like the ones who actually worked on Joss Whedon’s shows, some of whom cast these guys in the first place).
Also, now that these Nathan Fillion and Anthony Head have been cast in the movie (and replacing actors from the first one, to boot), the precedent has been set for further Whedon alums to be cast.
(Amy Acker, Alan Tudyk, Amber Benson, et al. Not knowing much about Greek mythology, I don’t know which roles they could play, but they’d be great in any case. And Fran Kranz could play one of those guys that constantly warns the hero that it’s too dangerous and that they should turn back, but the hero never listens. And Samuel L. Jackson could play some relative of the main character, existing to give advice and be awesome. The racial difference could easily be explained by the fact that this is set in a magical world. As could the random singing, and so on and so forth…)
Nathan Fillion and Anthony Stewart Head both appeared on Buffy the Vampire Slayer (the former only in Season 7), though they didn’t get to interact.
Nathan Fillion plays Dogberry in Joss Whedon’s upcoming adaptation of Much Ado About Nothing, and Anthony Stewart Head was Joss Whedon’s first choice to play Leonarto, but he wasn’t available during their short window for filming, so Whedon went with Clark Gregg (Agent Coulson from The Avengers and the wider Marvel movie universe) instead.
Apparently the second book doesn’t include interaction between the two characters of Hermes and Chrion, but film adaptations can always make changes to the source material, and it is a franchise, so who knows…
Maybe Nathan Fillion should guest-star in Merlin, perhaps as a knight who sings songs about how heroic he is.  And for a bonus Sherlock reference (it is a fellow BBC show, after all), other characters could refer to him as 'Sir Boasts-a-Lot’.
And, conversely, maybe Anthony Stewart Head should guest-star in Castle, perhaps as a slightly fusty expert in some field or other that’s involved in a case, who gets amusingly exasperated when Castle shows up and acts like he knows everything and it’s all a big joke.  So basically it would be a bit like Giles interacting with Anya or Cordelia.
Percy Jackson & the Olympians: The Sea of Monsters is an adaptation of the book by Rick Riordan, directed by Thor Freudenthal, and stars Logan Lerman, Alexandra Daddario, Brandon T. Jackson, and Jake Abel, all of whom are reprising their roles from Percy Jackson & the Lighting Thief, and they’re joined by Missy Pyle, Yvette Nichole Brown, Mary Birdsong, Nathan Fillion, and Anthony Stewart Head. The film is set for release on March 26, 2013 in the US, and a day later in the UK.