So we wanted to have some roommates, but we wanted for us to throw them in with other roommates first, and we see that. I think it's in The Freshman or Living Conditions where we see Willow with her room mates who are just partying wildly and she's holding one hand over her ear and has the phone pressed to her other ear.

BBC : Did you get any irate Cher or Celine Dion fans saying, "Why are you dissing our favourite singers, we think they're cool"?

Doug Petrie: As far as I know there's very little Celine Dion and Buffy fan overlap. That Venn diagram just doesn't intersect!

I hope that when we poke fun at another pop culture icon like Celine Dion that it's never mean-spirited. You know, it's done a little bit lovingly, because we're a pop culture thing ourselves. Some day someone will be poking fun at us, and we can only hope that it's in a good spirit. It's a joke and we hope that does come across.

BBC : Was your roommate the roommate from hell?

Doug Petrie: Oh yeah, I shared my freshman year with a guy named Mike Beck who, every night, would come in - and I was not a saint at all in college and certainly not my freshman year - but he would come in every night at around one or two a.m., the door would slam open and he would stand there with a grin on his face and he'd say, "Guess who's wasted?" I was like, "Oh no!"

The first time you go, "Oh that's charming, that's funny", and the second time you think, "All right, well it's twice in a week", and then it becomes, "Oh this is his standard line". It became dull, so yes, he was a roommate from hell... but we all had one.

BBC : Cathy was something of a demonic errant daughter with a, "Why are you out so late?" father fetching her back to hell. This highlighted the fact that that there seemed to be a few more "comic" monsters this year. Do you like to treat them in a humorous way sometimes or do you prefer your monsters evil?

Doug Petrie: I guess speaking just for myself - and this is not for the team or for Joss or Marti - I'm very comfortable with it. Unlike a lot of other shows, comic books or movies, we have a lot of room to run around and I think we would be remiss not to take advantage of that.

What happens is within any given episode of Buffy, you'll find that the first two acts are fairly comic, veering towards darkness and the second two acts are usually much darker and more serious. The stakes are high, the jokes dry up a little bit by the third and fourth acts and things become darker within an episode.

I think - and again this was not a conscious decision - that the season takes a similar shape. Things can start out light and fluffy and comedic, by the time you get to episode 22, they seem to be darker and more serious. Life and death is no longer a joke and the humour that comes up kind of pops up as comic relief later on in the season, whereas in the beginning of the season we could do a whole episode.

Again, I know that I'm teasing about season five, but it will become extremely dark and yet there will be episodes that will be funny. They will kind of pop up to remind the viewers that this show is not strictly any one thing. There will be tragic elements but if it were strictly a tragedy something would be lost, just as if it was strictly a comedy, something would be lost. So I think that the seasons, well... we always start out at spring and we go through summer and fall and we always end in kind of the dead of winter, so that's kind of how our seasons go.