ROBERT DUVALL has started to read lately. He says it's a novel idea. "A year ago somebody says, 'Let's buy Bobby a book for Christmas.' The other guy says, 'Why? He's already got one,'

Duvall picks his teeth with a plastic swizzle stick.

He has been seated at the banquette of an Alexandria restaurant for 20 minutes, and has ordered a Perrier and lime, a terrine of cold seafood and broiled monkfish. "Broiled easy, but very moist," he tells the heavily accented French waiter. "Moist. Broiled, but moist. Yeah."

He looks around the room. "This a French restaurant?"

It's not that Duvall is dumb. Even if he says "yeah" after every sentence, doesn't know what "droll" means and turned down the lead in "Jaws." ("Maybe it was dumb. I could've made a lot of money.")

Maybe he's just distracted. After all, he's busy these days promoting two films: the highly touted "Tender Mercies" and an offbeat film on gypsies that Duvall spent the last four years writing and directing, "Angelo, My Love."

His family calls him Bodge. It's a name that stuck after one of his brothers couldn't pronounce Bob. His laughter erupts in a machine-gun cackle from the side of his mouth. Like a fighter's laugh. Or a bully's.

"I'm a gentle guy," he says. "I'm not a fighter. If I see a fight on the street, I go the other way." He wolfs down the seafood appetizer. "I'm not a hard guy at all."

He's 52, with thin strands of reddish-brown hair teasing the freckled dome of his skull. He is tall and sinewy, with a flat stomach and surprisingly small hands. ("Yeah. They are.") His eyes are chlorine blue and set deep in their sockets with an explosion of wrinkles on either side of his pale cheekbones. The tip of his sharp nose is pink and he wears a faded blue shirt with a monogram on the breast pocket under a thin brown leather jacket.

A limestone cowboy.

"Average macho," he shrugs.------

Big, bad Bobby Duvall: a steely Marine fighter pilot ("The Great Santini"), a slightly crazed Vietnam colonel who loves the smell of napalm in the morning ("Apocalypse Now") and a hard-boiled, corrupt cop ("True Confessions"). All these roles so convincingly portrayed, Hollywood insiders say Duvall doesn't act. He just is.

"I think I'm instinctively sharp."

He's made 33 films in the last 20 years, won the New York Film Critics Award for best supporting actor as the cool mafia lawyer Tom Hagen in "The Godfather," been nominated for an Oscar three times, and played the title role in the TV mini-series "Ike" and he has a reputation as America's finest character actor, usually playing the unsympathetic second-lead with Valvoline in his veins.

He leans forward.

"The funniest story ever happened to me in this business? I never told this story much. The second show I ever did, I played a cowboy. I dressed up in black. It was in Santa Fe. I ride up on this big black horse and I had to pull out a gun. You know as kids, you play cowboys? Well, they roll the camera. And here I am, an adult man, 30 years old, for godsakes. Well, they say 'action' and I pull out my gun and go 'kkccchrr, kkccchrr.' "

He cackles loudly. "Kkccchrr, kkccchrr. The horse looked at me. The director looked at me."

Now the waiter's looking at him.

He is eating lunch with his younger brother Jack Duvall, a Washington lawyer, and talking about life and his latest role as down-and-out country singer Mac Sledge in "Tender Mercies." It's a welcome departure for Duvall, a role that taps his sexuality as well as his singing. It's a skin-tight persona, with a dust-bowl swagger and bowed legs and redneck twang, perfected in east Texas. He went there, found a man with the accent he wanted and got him to recite the entire script into a tape recorder. But the voice is only part of it. Mac Sledge is a blue-collar Kristofferson, with slicked-back hair and rawhide skin.

"This is the only film where I've heard people say I'm sexy," he grins. "It's real romantic. Rural romantic. I love that part almost more than anything."

Duvall doesn't play a role. He consumes it. Or it consumes him. ("You do become somebody else in a way. But it's like you don't," Duvall told an interviewer once.) In any case, his ability to stretch the limits of his range as a performer prompted film critic Vincent Canby to call him "one of the most remarkable actors in America today . . . I think he may well be the best we have, the American Olivier."

"I'm better than Olivier," Duvall says, with a cackle.

Is he kidding?

"I'm not a big Olivier fan. I don't know. He does what he does and I do what I do. He's not my favorite actor. And now, he's terrible when you see him in these parts."

He says he likes Gene Hackman. He likes Robert De Niro. "I used to like Brando, but he's lazy."

He fidgets in his seat, takes a swig of ginger ale and folds an empty pack of Sweet'N Low into tiny squares. Duvall doesn't seem too anxious to change his image to romantic leading-man status, up there with Redford and Newman and Hoffman.

"I don't want that," he says. "My career's on my own terms. I can play what I wanna play. I don't think those guys can play what I can play.

"I've gotten great parts. Better than anybody I know, almost. I get my own attention.

"I've gotten good recognition. I won't be ready to quit for a number of years. I'm always looking to improve. I could have had this position 10 years ago, but I like it better now. I feel prime now. Like I'm in the prime of my life. I feel right about things. When I can't improve any more I'll quit.

"I like the challenge. I like the challenge of doing different parts. You know, I'm going to tell you something very accurately. I somehow feel the older I get, the better I get. Whereas some other people dry up quick. I'm always trying to improve."

What will he be doing when he's 80?

"-------," he cackles. "I better be doing sumpthin'." He turns to his brother. "I like women that blush."

Born in San Diego in 1931, Duvall is the second of three boys. His father, Rear Adm. William Howard Duvall traveled around the country, finally settling in Virginia. Duvall and his brothers were known as Navy juniors, the socio-economic equivalent of Army brats. They played a lot of practical jokes, he says. "We used to put Tide in milkshakes for my mother. And we used to tape record my father snoring and then play it at the breakfast table."

He went to prep school in Severna Park, Md., then attended Principia College in Illinois where he nearly flunked out.

"I didn't have good study habits," he says. "I don't think I was a dummy. I was probably accused of being a dummy." His parents suggested he try acting. "I guess I had the talent for it."

"He was just gifted in that respect," his brother nods.

After graduation, Duvall went in the Army for a few years, then joined the Neighborhood Playhouse in New York where he met screenwriter Horton Foote, who gave Duvall his first break, choosing him in 1963 for the part of the reclusive neighbor Boo Radley in Foote's screenplay of "To Kill a Mockingbird."

Duvall's career took off, with a string of film credits, including "The Chase," "Bullitt," "True Grit," "M*A*S*H," "THX-1138," "The Godfather, Parts I and II," "The Great Northfield Minnesota Raid," "The Outfit," "The Conversation," "The Killer Elite," "Network," "The Seven Percent Solution," "The Eagle Has Landed," "The Betsy."

Does he like his own acting?

"Some of it, yeah."

Does he think he's good?

"Yeah."

Great?

"I'm capable of it."

His worst performance, he says, was in "The Pursuit of D.B. Cooper." ("I did it for the money.") His best performance, he says, was in "Tomorrow," a 1972 film based on a Horton Foote screenplay that was hailed by critics, but never received wide distribution. Horton Foote also wrote the screenplay for "Tender Mercies," the most enthusiastically received film Duvall has acted in since "The Godfather," he says. The Los Angeles Times called it "superlative," Time Magazine hailed it as the best film of the new year.

Duvall seems unfazed by this latest gush of praise.

He doesn't drink, smoke or own a car. He says he's been depressed and broke a lot, but never went into therapy. He likes to sleep, play tennis and says his favorite singer is Merle Haggard. "George Jones is going around telling everybody Mac Sledge is him. But it's not. When Willie Nelson saw the film, he said, 'I can't tell you how much you remind me of Merle up there.' "

Duvall also does a terrific imitation of Brando and says he learned his acting skills from his mother. "My mother's a terrific mimic."

He owns a co-op on 86th Street in Manhattan and when he's on the West Coast, he rents a house. He says he eats out six night a week. "We have world-class parties. I love to hold court with friends, sing, have belly dancers. Sometimes we have opera nights."

His brother Jack smiles. He's the opera singer.

"Caruso used to live in my apartment," Duvall says.

He's not religious. "My wife says I'm spiritual. Whatever that means."

He is conservative. "My wife's a liberal. She's loosening me up a little."

His wife is Gail Youngs, 29-year-old actress and sister of actor John Savage. She and Duvall were married on a small island off the coast of Maine last fall. "I always said I wouldn't marry an actress, but I did. I wanted to settle down again. I think she's good for me. Yeah. She's good for me." It is his second marriage. In the early '60s, Duvall married former Jackie Gleason Away-We-Go-Girl Barbara Benjamin. She and Duvall lived in upstate New York before their divorce in 1980.

Does he have any vices?

"I commit adultery," he laughs. "Naw. I don't."

He picks up the swizzle stick and stabs the tablecloth. "I don't have any vices. Maybe sleep. I'm lazy."

Still, Duvall managed to stay awake long enough during the last four years to write and direct his second film, "Angelo, My Love." His first film, "We're Not the Jet Set," came out in 1977. It was a documentary about a rodeo family. It opened and closed the same day. Duvall used his own money to make the film and swore he'd never do it again. "Angelo, My Love" is a film about gypsies, and stars Angelo Evans, a 7-year-old, dark-eyed gypsy Duvall met on the corner of 71st and Columbus in New York.

Duvall was hooked. "I said to myself, 'Here I go again.' " He bankrolled the project, spending $1 million of his own money. It opened in New York this week and will be screened at the Cannes Film Festival next month.

Duvall may be fascinated by gypsies because he's a maverick from the Hollywood scene, a town he says is "inundated with hacks." Or maybe because of his migratory childhood.

"Yeah, maybe. I'm kinda transient. I'm on the move a lot. But I think what attracted me to the project was because I'm an actor first and if I direct it's got to be an extension of acting. It's got to be like a quest for behavior. A lot of films I don't like. Especially old Hollywood films that people usually revere because there's so much artifice involved. I don't like that. On one hand, you're asked to accept that. On the other hand, you're asked to excuse certain things. I don't think you can do both. Don't ask me to revere something if I have to excuse certain things. But I saw something real in this kid. I never met a kid that unique before. I always wanted to do a movie with a kid in the lead."

As an actor, Duvall is known as "The King of the Off-Camera." He can be trouble on a set. "If I can't get things my way, I'll do anything to get it," he says. "It's all for the good of the film. I consider myself a radical, maybe not a radical, but very unconservative in my work. I'm not a conservative actor at all. I'll be an anarchist on the set if I have to, to get what I want. But in life I'm not like that. You know, I follow the system."

But the star system is something he doesn't subscribe to. Which is maybe why he hasn't won an Academy Award.

"So what? You've seen some of the people who have won 'em. It's a very strange business. When I went in to do 'Santini,' I saw the producer and he shook my hand. Before I was in the chair, he said, 'Well, it may be a little early but they're talking about Oscars for this one.' I couldn't believe it! We hadn't even begun to rehearse or roll the camera or anything.

"It's a lot of hype," he says, the swizzle stick in his mouth. "It's a big show. I don't know what it really means. If it means you're accepted by your peers, that's one thing. But I hear a lot of trade people go home and hand out the ballots to their family, have their kids vote for 'em."

He stands up. Lunch is over.

Later that night, he hosts a screening of "Tender Mercies" for his parents and relatives in Washington. Jack Duvall stands at the door. His brother, the star, gets patted and pinched by aunts and uncles who call him Bodge. His father learns that a reporter is there. "Give 'em hell," the senior Duvall says gruffly. Then he comes into the screening room and yells in a Great Santini voice to his two sons, "Let's get this thing going, boys."

The credits roll, the audience settles back and Robert Duvall sits by himself on a folding chair in the back of the theater, elbows on knees, his mouth resting in one upturned palm. He watches it intently, gauging the reaction.

Earlier, he was asked what he might be doing had he never gone into acting.

"I don't know," he mused. "I might be a fairly successful high school football coach.