If you needed a reason to watch ABC’s romantic comedy detective series Castle (starring Nathan Fillion) check out the following promo.

We just told you the other day about Fillion donning the Capt. Tight Pants outfit again and showed you a picture but now, thanks to ABC.. we’ve got video!

Fillion’s character is decked out as Mal Reynolds for Halloween and referencing a certain teen-vampire-slaying series in which he once had a prominent role, and also a certain vampires-versus-werewolves franchise that he had nothing to do with.. it just pushes his geek/sci-fi cred meter up a notch. (Like Fillion needed any more cred)

The Castle Halloween episode, “Vampire Weekend,” airs Monday at 10 p.m. ET/PT on ABC