Re-watching all of Buffy the Vampire Slayer, Angel, and Firefly since January has allowed me to pick up on the one theme that they all have in common: family. Not necessarily the one you're born with, but always the one you choose and chooses you. At their cores, the shows created by Joss Whedon are all about families of choice, from the Scoobies to Angel Investigations to the crew and passengers of the Serenity, outcasts all but outcasts who come together as families. I think this is where a great deal of the emotional power in Whedon's work derives from.