The enthusiastic speaker? James Marsters, who has made the part of Spike, aka the two hundred year old William the Bloody, his own on Buffy the Vampire Slayer. The living proof of the axiom that you should never judge an actor by the character he plays, James sits in The Cheesecake Factory in Marina del Rey, exhausted after a long day at Fox's studios where photos for the new season of Buffy have been taken. Casually dressed, his hair still bleached blond, it takes a moment to realise that it would only take him a moment to slip back into the character and look for a tasty neck to feast upon.

Coming from a theatrical background, James arrived in Los Angeles with a plan to "do like five years, save a good amount of money and go back to the theatre. I'd be someone's sidekick - I'd be ALF's sidekick - I don't care. I want some good money then I'm bucking out and going back to the theatre, and have savings." He never expected to be so fortunate, and throughout our conversation, it's clear that he can't believe his luck. "I didn't want to be poor all my life," he maintains. "So to land here and have good writing: I didn't come here for that. I came down and discovered that you can have your cake and eat it too."

"The part of Spike came about from "one of a hundred auditions. I think I just had a really good audition that day. You have a lot of auditions; you audition so much. That's the hard part of acting. There are actors in LA who have, like, three films coming out and they feel, they're just not making it, because 90% of the time you walk out the door to go to work, which is your auditioning, and you're a failure. It's weird that way. The writing was very good and I could unleash in a way that the character could go theatrical. He's not a pedestrian character, so he's kind of theatrical, and coming from the theatre, you try to be subdued for film - you try to simplify and try not to go over-theatrical - and then they give you a role where you can go over the top! I was at a good place in my life, and I had a really fun time."

Although Spike is now indelibly engraved on the memory as the white haired, English accented (although from quite where in England is anyone's guess) vampire who sweeps into Sunnydale determined to have fun, Joss Whedon apparently wasn't certain originally how he wanted him to appear.

"They had me do the character Southern as well; their first thing was British, but they also wanted this Southern thing. I'm so glad they didn't. I think they would have killed me off after a couple of episodes. They were supposed to kill me off but they didn't. Weird things: if he had been Southern, it might not have worked so well and they would have killed me. If they had decided to have black hair instead of white hair, they might have killed me off. If they didn't have the long coat, they might have killed me off..."

The instant rapport between James and Juliet Landau, who plays Spike's vampire lover, Drusilla, sealed his fate. The audition scene, taken from School Hard, was Drusilla's first entrance, where the bond between the two demons is clearly demonstrated. "We sort of went for it. There was a trust there, instinctually, I guess. We almost kissed then turned out and looked at the [Anointed One] - we just did that at the audition."

At the end of What's My Line?; Drusilla is cured - partially - but Spike is crushed by a falling organ, and spends much of the rest of the season in a wheelchair. "I was supposed to have died, that was the plan," James reveals. "What do you do with the character of Spike if you don't kill him like planned? Drusilla's supposed to go with Angel when Angel goes bad. That was what was supposed to hurt Buffy the most, right? That was radical. I so did not want to be in that wheelchair, I hated that wheelchair, but I didn't realise it was that or kill me."

Apart from when he was spending time recovering, Spike loves nothing more than a fight - in fact, it is the 'adrenalin' flow from his fight alongside Buffy and Angel in his sole Season 3 appearance, Lovers Walk, that snaps him out of the drunken depressed maudlin state in which he has wandered around Sunnydale. James shares this side of his character. "I like fight choreography, because you're swinging around. There's so much illusion happening in a fight. It's all about making it look like you're punching someone when you're not. It's like sleight of hand. It's like a little theatre... I like creating an illusion, that's what I love about it. If your personal life is being hard, you can make a life experience that you can control."

In particular, James enjoys Spike's battles with Angel, because the directors allow James and David Boreanaz to fight each other. "Usually they have a stunt man fight an actor. They don't usually let two actors fight each other, make a mistake and hurt each other. You're nearly always seeing over the shoulder of one of them onto the other actor. But they let David and I fight because they can get more coverage in a scene, but also because we don't hurt each other."

James shares David Boreanaz's willingness to jump in to do stunts. "The stunt people are great, but you can't get around the fact that you are dashing around the set. No, you aren't really being hit by a two by four, but you are careening into the hood of an automobile twelve times."

"I can kip," he then announces proudly, and promptly explains. "This is when you're knocked down, and you put your legs over your head and you pop back real fast. That's apparently a big deal thing, and it looks all kung fu. So I was talking to a new stunt Spike... I don't know what to call him. He's not a double, he's part of the character of Spike. He's the guy that flips around. I like to learn as much as I can, so I can be in it as much as I can. He said, Can you kip? I said I didn't know, so we tried and I could. So I was all proud and reported to the set, and kipped eleven or twelve times... The next morning, I swung my legs out of bed and I folded to my knees. I couldn't stand up. I was hurting so bad. I went to work and the first thing they said was, We're going to have you kip!"

Like all of the other actors on Buffy, James is full of admiration for everyone else on the set. "There are no assholes. People have fun. It's weird. There was only one... just one guy who came in for two weeks. The hours get long and you get a little bit over it, and this guy came in and reminded us, and it was like, Oh my God, who let him into the sandbox? We usually have so much fun around here, and it reminded me, My God, I haven't met an asshole in ten months. It extends to the crew, it extends to everybody who's there. The production people up in the offices, everybody, I think, is hired with that in mind. Your social skills have to be pretty good too. I think that they realise that we have to live with each other. Some people don't take that into account."

Unlike some members of his profession, James is full of praise for his onscreen partners, compliments flowing from him throughout the evening, particularly for David Boreanaz and Tony Head, whose role as Giles James does not envy in some ways. "Tony has all the exposition, which is always the hardest part of doing any script. It's not the action, it's the context of what is going to happen. Sometimes those are the hardest scenes to act because there's less story to them. It's like in a theatre piece: actors really hate having to deliver exposition. It's called 'heavy lifting', and that's his job. Spike's a badass, because he said so. Tony does that great. He talks like Spike - in life, he sounds pretty much like Spike," he adds. "He just puts the plum in his mouth for the role. I would have loved to have seen his Rocky in Rocky Horror. That would have been great. I want to see him in mascara!"

James found a different sort of camaraderie on his next job after filming Lovers Walk, when he visited the Vancouver set of the third season of Millennium, playing Swan, a deranged Army veteran who kidnaps Peter Watts' daughter. "I got the sense that they were good people who had been worked within an inch of death. Apparently on all Chris Carter's series, they shoot so many angles, they can make two shows for every one that they make. They could cut a whole different version from the angles - in the editing room they have so much stuff to work with - so consequently, the workload for the actors and the grips and the director is just doubled. They work so fast."

"That was what was so cool about it. They were so self-sufficient in the setting up of the shots that you didn't have a whole lot of downtime. It was hard to work but it wasn't start and stop, you just kind of kept working. The other thing that burned everybody out was that they spent four days out of seven on the road. When you're on a sound stage, you're at home; it's long hours but you've got your stuff there. When you're on location, it's like camping. It's cold and it's raining sometimes. We were in an insane asylum that had been opened up for filming - they put me in a van and took me out somewhere! It had no heat and it was like, I don't know, maybe 20' inside. They had a lot of space heaters and stuff but we were there for about 14 hours. I was okay because I didn't do that all the time, but man, they were really good people but they were just on the verge of losing it."

"I learned a valuable lesson doing Millennium, actually. I had just done the Buffy episode where I am a weeping mess, and I was so proud of my emotional acting. I was really crying. I really was going there with that pain, and you watch the thing, and the scenes are all about someone crying. Then I went to Vancouver, and I cheated. My character is supposed to be having an emotional breakdown, and they just squirted this menthol stuff in my eyes, and I felt guilty about it. Then I looked at the footage, and the scene is about crying, but there's a lot of other things going on. I could act all the other stuff, not concentrating on whether I could cry or not. So I'm cheating from now on."

"Brando says an actor shouldn't have to act. Film is very young. I think Brando had it right. I don't do any of this, but I wish I had the bravery to: he was writing his lines all over the set - he wanted to write the lines on the other actor's forehead. When he's looking up at the ceiling, he's looking at lines. Film is nothing like stage at all. We're still applying stage acting techniques."

"[The menthol] is a great technique. You can't tell. It works. When Brando had to die in Mutiny on the Bounty, he submerged himself in ice water, put the costume over snow packs, so he was going truly into hypothermia. He was medically dying. I don't know if I would ever do that, but he didn't, as an actor, have to replicate dying. He could act everything else, all the other things the actor was trying to establish. So yeah, I shall just use fake tears...."

Despite having worked in television for some time now, James feels he is just scratching the surface of the differences between stage and film acting. "I think I came down here a little arrogant, actually, not recognising that learning how to act for film would be such a huge challenge," he admits. "It was fascinating, the things you can do on film. The amounts of your job you have to cut away. On stage you have to worry about where the audience is looking, who has focus, how to make an entrance, how to draw the eye and the ear radically up stage right. My first entrance in Buffy I did that, I made a mistake. I talked really loud, like I was on stage. I thought, I'm wearing a microphone. Everyone else in the scene is talking normally, and who's shouting over in the corner here?!"

Whether he's acting on stage or on screen, James is fulfilling his ambitions. "I liked the magic trick of it," he says of his desire to act. "You set up this magic trick, sustainable magic that you can repeat on a regular basis. It's like creating an amusement park ride. You can make it exactly what you decide to make it. Give someone the experience you want them to have - or you try to do that."

"You can't control someone else's experience, but you can take them on a journey."