WASHINGTON - In a postcard-perfect little yellow house with a baby stroller on the front porch, there lives a man, his wife, three young children and about 20 elves.

The couple and their kids are friendly and well-known around the neighborhood. The elves, who aren't always so friendly, are well-known around the world. One is so universally despised that people regularly conspire to kill him. A foul-mouthed kid just moved into the house, too, but he spends most of his time wandering around post-nuclear Washington in a different century.

This becomes more than mildly interesting because the same elves might infest your own living room and, if not, surely they are next door or in a house just down the block. And the potty-mouthed kid is going to show up in homes all over right around Dec. 26, once Santa has completed his rounds.

Craig Sechler, nice guy from Washington, is the voice behind these and dozens of other characters in interactive video games, an intriguing, sometimes eerie, always challenging subculture that is as invisible to many people as it is all-consuming to others.

"There are just two kinds of people: those who do play and those who don't," Sechler said. "Eventually it will be just those who do."

Sechler is the voice for two of the animated characters in the video game Fallout 3, a sequel long awaited by gamers and produced by Bethesda Softworks in suburban Maryland. More than half a million people bought it within five days of its debut in October.

The game is set in Washington, 200 years after the city was devastated by a nuclear attack. A blitz of advertising in the Metro Center station so startled some riders with depictions of the capital in ruins that one man complained, "We do not need a daily reminder of what our worst fears look like."

If that's what our worst fears look like, then they sound like Sechler, Wes Johnson and 33 other local professional voice actors who took part in the production. The biggest-name voices among them are Malcolm McDowell, Liam Neeson and Ron Perlman.

Voice-over actors are a constant in modern life. They narrate documentaries, promote television shows, deliver advertising messages on radio and television, and are the voices-without-a-face on game shows. Almost every American alive has heard the booming voice of Don Pardo, but few have ever seen him.

"It's terrific as a performer because you can play a whole lot of roles without ever looking the part," said Johnson, 47, the voice of Mr. Burke and Fawkes in Fallout 3. "You know how people say, 'You have a face made for radio?' Well, that's me."

Video games present a few new twists on a profession that's been around at least since the introduction of the Victrola. Unlike most voice work, there's no rehearsing of lines. With so many lines to be read by a major character in a session, there's no time for practice.

"They hand you something that's about the size of the phone book and you spend the next four hours doing enough variations on it so that the gamers won't get bored," said Johnson, who is also the voice of hockey's Washington Capitals at the Verizon Center.

The passion that players bring to these games translates into a cult following for their characters.

Fallout 3 is too new for anyone to predict which characters fans will latch onto, but both Johnson and Sechler did voices for the game Oblivion, one in a Bethesda Softworks series called "The Elder Scrolls" that has sold 3.3 million copies.

Try Googling one of Johnson's characters, Lucien Lachance, the evil leader of the Dark Brotherhood. You will get about 69,000 hits, several leading to entire Web sites and chat rooms devoted to discussion of Lachance.

"I went into one of the [chat rooms] once and said, 'How you guys doin'?" Johnson said. "And they responded, 'The Dark Lord has arrived.' Of course, they didn't know their Dark Lord was wearing a pair of shorts and an oversize T-shirt at the moment."

Sechler, 57, claims to have the "voice of a 12-year-old," but the truth is he can muster just about any voice he's asked for. He is the voice - or voices - for an entire race of elves in Oblivion, which has a vast following. When he auditioned, Sechler found one of the elves "really annoying."

"They said, 'Yes, we want people to hate this character,' " he said.

Thus was born Adoring Fan, a whining sycophantic elf who follows the game player relentlessly, pestering the player with praise until it becomes unbearable. On YouTube, Oblivion gamers present their self-made productions on killing Adoring Fan. (Hurling him off a cliff is a favorite.) How do they create their own videos and voices that seem no different than the real thing?

"I don't know, but, hey, they're geeks," Sechler said.

The video game adventure began for Sechler with a call from an agent: "The last time I'd looked at games it was all just guys saying 'Uggel' and falling dead."

Now Sechler spends four-hour sessions in a tiny sound booth in suburban Rockville, Md., delivering literally thousands of lines as audio director Mark Lampert eggs him on.

"It's nothing like stage acting or film acting," said Sechler, who has done both in a career that began when he was 7 and who played the original Big Kid on the Lucky Charms cereal commercial. "There are no rehearsals. There are just so many lines, and with most of them you're killing people or being killed. I was in the booth for 31/2 hours the other day, and by the end of it I was like a wet rag."

Johnson said his three teenage sons take particular delight in playing Oblivion.

"They get to chop up Dad with a broadsword," he said. "Not many kids can say they've done that."