As the White House lurches through the drama starring its national security adviser, Richard V. Allen, there is a subplot playing out in the wings. Its lead character is Fred F. Fielding. His job: counsel to the president, the man who must advise Ronald Reagan about the legal implications of the FBI investigation of Allen. His close friend: the subject of the investigation.

Allen himself calls the bond with Fielding "strong and important."

"Which makes all this very bizarre," says a senior White House aide.

Fielding and Allen have known each other since they were both White House staffers in the the early Watergate days. That's when Fielding, as John Dean's assistant, put on surgical gloves to inspect the contents of Howard Hunt's safe. This past week, talk of Allen's safe -- and whether it contained $1,000 or $10,000 in payment from Japanese journalists for an interview with Nancy Reagan -- has floated through Washington like the ghost of scandals past.

"It's horribly disruptive," says Fielding, "and so it's de'ja vu to that extent. There's constant turmoil and press inquiries and that sort of thing, but I certainly wouldn't compare this to Watergate at all. Certainly, I don't expect the president to ask me to go up to Camp David to write the definitive report on the Allen matter as Dean did on Watergate . . . What if he did? Jesus. I'd suggest that he pick another spot."

Fielding, as Allen's lawyer, was with him in 1976 when Allen was accused in a Senate hearing of soliciting a $1-million bribe from Grumman International, a charge that was never proven. He was with him in 1980 when he resigned from the Reagan campaign after conflict-of-interest charges were reported in The Wall Street Journal, charges that were also never proven.

And Allen was with Fielding in the hospital, when Fielding was recovering from a pulmonary embolism that almost killed him. Allen smuggled in Chinese food and Japanese beer. "Probably against the rules," says Allen.

They've been together again the past week, like good buddies when one is in trouble -- on the phone, in their offices, exchanging quick words at staff meetings or in the stairway that connects Fielding's second-floor West Wing office to Allen's basement quarters. Allen is the noisy life-of-the-party ("Hiiiiiii, I'm Dick Allen from Arlington, Va.," he is famous for saying, repeatedly, to other White House staffers) with a temper that explodes; Fielding is the placid, controlled sounding board who says with a lawyer's caution that he is "concerned" but not "anguishing" about his friend.

This time, says Fielding, his role is altered. "Dick understands that there is nothing that I cannot disclose to the president," he says. "The main point is, Dick has released me of any confidentiality. There is no conflict of interest. My client is the president."

Still, White House aides are keenly aware of the friendship. Last week, Fielding released a statement saying that the continuing FBI investigation of Allen had found no law broken, only to have the Justice Department contradict him and say the case was still open. White House aides now defend him and say he was given incorrect information. But they also make sure to say he has attended only a "small number" of meetings about the Allen case. And it was presidential counselor Edwin Meese III, not Fielding, who talked to FBI Director William Webster about the probe.

Back in January, just prior to coming to the White House, Fielding advised Allen on how to avoid conflict-of-interest problems with former business contacts, including the Japanese. "Rest assured, we've been over that very carefully," Fielding said afterward.

Question: How did this happen, then, if they went over it 100 times?

"Now," sighs Fielding, "it's 101."

Saturday at the office. There is opera and news of the Hill's funding-bill fight coming softly from the radio. Fielding is dressed in a plaid shirt, camel blazer and blue V-neck sweater, an alligator on its left breast. John Dean described him as looking like the actor George Hamilton. Today, at 42, Fielding has accumulated some padding. "How about Robert Mitchum?" he suggests.

He has graying hair, a steady gaze, a good dead-pan delivery and a reputation at the White House for solidness and excellence. "I hired him and he's a goddamn fine White House counsel!" says a loud chief of staff James Baker, friendly but tired of questions about Allen.

"He's a fine man and a good lawyer," says a tight-lipped Attorney General William French Smith, also tired of questions about Allen.

Unlike some other White House counsels, Fielding rarely gets into policy decisions. "Different people have held that job and played different roles," says a senior White House aide. "Lloyd Cutler held that job and served as counsel to the president. Phil Buchen held that job for Jerry Ford as friend to the president. He wasn't as high-powered as Lloyd Cutler. But Fred's job description is more of a narrow, legal one."

Fielding's job runs from reviewing CIA Director William Casey's personal stock holdings to wondering what to do about a magazine article sent to him entitled "Ronald Reagan's Secret Stag Film." He shows it, complete with pages of pictures, then rests his head on his hand.

His salary is slightly above $60,000 a year, a huge cut, he says, from what he made in private practice. "I don't know how long I can afford to stay in this job," he says. "You say you're only going to dig into your savings a couple thousand each month, and then the damn refrigerator goes out. Twice a month, I just go out to the corner of 17th and Pennsylvania, give my check to a cab driver, and he cashes it."

Fielding is from Bucks County, Pa., the son of an advertising and public relations man. He went to Gettysburg College and the University of Virginia Law School, then met his wife, Maria, while he was a captain in the Army at Fort Meade. "Yeah, she was passing out doughnuts at the USO," he says, grins, then amends: "No, she was really an airline stewardess." She was. They settled in Philadelphia, he practiced law, made money, then got a recruitment call from the White House. John Dean needed an assistant.

Fielding didn't resign until January of 1974, when he went back into private practice in Washington as an expert on government ethics. He surfaced again for Reagan's transition, serving as the conflict-of-interest specialist. A week after the inaugural, he was named White House counsel -- the same week he'd been assigned to a temporary office in the Old Executive Office Building. It was John Dean's.

"It was a rather strange set of circumstances," he says, then stops and gazes. Nothing more comes out of his mouth except smoke from one of his Marlboros.

The only Watergate memento in his office is a framed "Berry's World" cartoon. "Too bad!" says the cartoon interviewer to an eager young interviewee, "you got a beautiful resume' here, kid -- except for bein' a former member of the White House staff!"

Another Watergate reminder, which Fielding says he's only read bits of, is "Blind Ambition," Dean's best-selling opus. Fielding pops up frequently, especially in a memorable scene just after the 1972 Watergate break-in. Dean writes:

" 'I guess we better go through this stuff from Hunt's safe,' I told Fielding after Gordon Strachan and Howard had departed. We pulled up chairs, took a carton, extracted the contents, item by item, and examined them like archeologists. One box was filled with junk from Hunt's drawers and shelves -- pencils, stationery, paper clips, even a blanket. We plowed on . . .

" 'Wait a minute,' said Fred suddenly. 'Wait a minute.' He went deep into concentration. 'John, this stuff is sensitive. Don't you think we ought to be careful?'

" 'Yeah, I guess you're right.' It hadn't occurred to me. I had been caught up by curiosity.

" 'I've got an idea,' said Fred, jumping up to leave. 'Hold on. I'm going to see Doc Ward.'

" . . . Fred returned triumphantly with two pairs of transparent rubber gloves, the kind used for rectal examinations. 'Here,' he said. 'Put these on. We won't leave any prints.' "

The White House had directed the safe-opening, and Fielding wound up supervising it. Fielding was never implicated in Watergate, but he testified in May 1973, that he was used to relay messages he didn't understand between political operatives. He also testified that he didn't realize when he carried a package from the Committee to Re-Elect the President to Dean's White House office that it contained $22,000 in cash.

And he has said, many times, that he is not Deep Throat, the Watergate source for The Washington Post. But it's lore around Washington, fueled by a favorite Fielding story that when he was in the hospital with the pulmonary embolism, he announced that he was on his deathbed and so was admitting to the world that he really was Deep Throat. He then cackled uproariously.

True story? he's asked in his office.

"Probably so," he says, only slightly embarrassed.

He leans back in a thick chair, behind a massive wooden desk. The office is done in gold wall-to-wall carpet and wood paneling. Over in the corner is -- a safe.

"That's nothing," he says. "When I came into this office there were five damn safes here. Lloyd Cutler had them. There was even one down here." He points below his desk.

Then he smiles. "But there's not a shredder in here," he says.

Fielding lives in Arlington with his wife and two young children. He hangs out at Joe and Mo's, the trendy bar and restaurant that he co-owns. He's had dinner with Allen there, although they sometimes go to a favorite Allen sushi place up on Wisconsin Avenue.

Fielding, ever the lawyer, won't discuss specifics of the Allen case. But he will compare the two administrations and their responses to scandal.

"Here you've got something that's what I might call a runaway story," he says. "Where in the other administration you had conscious, concerted effort to contain a situation . . . I don't perceive the siege mentality in this administration, and I certainly did in the Nixon administration."

The Allen case, he says, "is way out of proportion, from what I know."

Does he know everything?

He answers, ever the White House counsel. "How do I know if I know everything?"