There's very little "new" that's brought to the zombie plate here. [The Walking Dead] is kind of my effort to canonize zombie lore. Vampires have a set bunch of rules, werewolves have a set bunch of rules—but a lot of time, when people try to do something with zombies, they try to reinvent the wheel ... It's confusing, and they have to explain it all. So I decided to start with the base, core—what I consider to be the ideal, perfect zombie—and go from there.

You've been writing The Walking Dead since 2003. What's it like seeing actors play the characters you've written about for the past seven years?

It's extremely bizarre. You're opening it up and letting other people play with it ... In all cases, there have been things that have surprised me, and things where I've been like, "that's really cool." There are certain movements that Andrew Lincoln [series protagonist Rick Grimes] will do that are unique to him—or unique to Rick, they're not even things that he does in real life ... Comic book panels aren't moving, so it takes a lot of space to do subtle actions like that, and that doesn't make it into the comics very often.

Does it bother you that the TV show's plot has diverged from the plot of the comics?

If anything, I think there are too many scenes from the comic that made it into the show.

Were there any specific scenes from the comics that you were disappointed didn't make it into the series?

Anything that I wish had made it into the first season will probably make it into the second season. If there's anybody out there who's saying, "Ugh, they should have done this scene, they should have done that scene" we'll get to it eventually. Don't worry.

What about a favorite scene that wasn't in the comics originally? There's a lot. All the stuff that was added about Morgan [Lennie James] in the pilot episode, with him trying to shoot his wife and not being able to, that's not in the comic. The scenes with Carol and Ed [Melissa McBride and Adam Minarovich] in the fifth episode, when she drives the pickaxe into his head after he dies. That's not in the comic. Anything involving the Dixon brothers, Merle and Daryl [Michael Rooker and Norman Reedus]. There's a lot of awesome stuff being done with those characters in the first season, and those are two characters that aren't in the comic at all.

Would you ever write any of the show's new characters, like the Dixons, into the comics?

It's something I've thought about. There hasn't been a lot of room for it right now, with everything that's going in the comic series, but it's something that I'd be open to, if the story was right and it all made sense.

Let's talk about the events of last night's finale, "TS-19." The comics avoid revealing what caused the zombie outbreak, but the TV show's finale gave us what was actually a fairly coherent medical explanation. Can you explain that decision?