SEVERAL YEARS ago Sen Richard Lugar (R-Ind.) took the advice of a friend and shaved off the top of his eyebrows because he was told they made him look sinister. He wasn't wild about the idea, says an aide, but it did help him retain his image as the Seante's shy boy scout.

But these days people are beginning to wonder about that angelic image.

Here's one example why:

Shortly before he shook up the GOP this month by wrestling control of the powerful National Republican Senatorial Committee from Sen. Bob Packwood (R-Ore.), one of his moderate colleagues, Lugar shrewdly set out to get at least one liberal swing vote.

Word began circulating that conservatives, unhappy that President Reagan planned to attend a fund-raiser next month for Sen. Charles Percy (R-Ill.), were pressuring the White House to cancel. Percy, it seems, may be challenged by a Reagan conservative in the primary.

Lugar called the White House on Percy's behalf.

"We wanted to make it clear to Percy that this was going to be our approach to problems like this," said Mitch Daniels, Lugar's top aide. "Sure we told Percy . . . We weren't shy about it."

Lugar won Percy's vote and he went on to defeat Packwood for control of the senatorial committee in what was seen as a test of the president's clout in the Senate. He went after the job with a vengeance. It is a rare moment when senatorial courtesies are eschewed and members of the same party challenge each other. But in a closed-door session, the Senate Republicans voted 29 to 25 to place Lugar in the powerful job, which throws him into national focus and allows him to control millions in campaign funds.

Common wisdom has it that the White House set up Lugar to challenge Packwood. Sen. Paul Laxalt (R-Nev.), Reagan's best friend, nominated him -- a clear sign of White House interest.

And the White House had reason to be interested. The administration had been unhappy with the maverick Packwood, who openly challenged the president -- opposing the AWACS sale, efforts to restrict abortion and charging that Reagan advocated policies that alienated blacks, women, Hispanics and Jews.

"Of course, we're more comfortable with Lugar," says one White House official, adding that the White House did not ask Lugar to challenge Packwood. "Anyone would be more comfortable having their own supporters in crucial leadership positions than someone that doesn't support the president."

But many who know Lugar say he is no one's errand boy. Fresh out of his own Senate campaign, he is described by aides as extraordinarily self-controlled and disciplined. He said he simply thought he could do the better job.

"I had no particular argument against Bob Packwood wanting to do the job," said Lugar, 50, last week, sporting a navy tie with tiny GOP elephants prancing across it. "It's just that I have more opportunities for the moment to be effective with this president, with Senator Laxalt, and I think with the rank and file of the Republican Party nationally. I think that's important.

"We're pulling together and we need to have a unified campaign in which we're all going to have very great trust in one another. And if any of the advice and counsel I have is going to be effective, it is based upon that sense of mutual trust and confidence, and the fact that I'm a hard worker for the whole team."

"I don't think you could have found another person in the Senate that could have beaten Bob Packwood," said Sen. Slade Gorton (R-Wash.), who nominated Packwood. Lugar "doesn't get involved in egos or personalities . . . I have no fear that he'll slant support in favor of certain candidates."

Although the vote was not split along ideological lines, some Republican moderates were none too pleased with Lugar's close ties to the White House.

"At the time I was making the decision, I thought it would be nice to have someone with a little distance from the president in terms of fund-raising," said Majority Whip Ted Stevens (R-Alaska). "Packwood is identified strictly with the Senate, no question about it, not the White House. There are 19 members up in '84 and when the president is running, everyone is always so busy raising money for him that someone has to worry about the Senate. Bob Packwood had the ability to raise money nationally. Lugar can probably do it too . . . I hope so. I'm up for reelection."

Lugar dismisses the notion that he'll hold the money hostage if senators don't support the president's programs. "Each senator has his own vote and his own conviction," he says. "We're going to fund every single incumbent to the fullest extent we can."

This kind of aggressive internal wrangling isn't new for Lugar, even though Senate colleagues commonly refer to him as a "straight arrow" and "wooden."

A decade ago, as mayor of Indianapolis (when he was known as Nixon's favorite mayor because he was in and out of the White House so often), he made a similar startling move at the Conference of Mayors' annual meeting. He challenged John Lindsay for the top conference job after Lindsay had been selected by the nominating committee for the post. Lugar won.

A Phi Beta Kappa graduate of Denison University in Granville, Ohio, and a Rhodes Scholar, Lugar started his business career by managing the family business -- Lugar Stock Farm Inc., a 600-acre farm in Indiana, and Thomas L. Green and Company, which manufactures food machinery. He took on his first elected office in 1964 as a member of the Indianapolis Board of School Commissioners.

Three years later he ran for mayor, and served until 1975 when he unsuccessfully challenged Birch Bayh for the Senate. In 1972, he defeated Vance Hartke. He is said to be a fearless campaigner, never using a prepared text in speeches -- even when he is delivering lay sermons to his church's congregation, as he often does.

"If he were a Democrat the press would have canonized him by now," says one aide. "But some people think he a pushover . . . He's very calculating . . ."

For instance:

* Lugar would regularly tweak Birch Bayh when they served in the Senate together. One way was through Lugar's newsletters to Indiana constituents explaining an issue and how Lugar voted. Then it would reprint the entire Senate roll call just to show that Bayh voted differently.

* When Lugar took over the chairmanship of a Banking subcommittee last year, he found himself in disagreement with the committee chairman, Sen. Jake Garn (R-Utah), over the hiring of a staff director. When Garn held firm, Lugar refused the chairmanship. Eventually a compromise was worked out and Lugar took the job.

* One minute he is rambling on about the well being of the human race, and the next minute he shocks the Senate by coming up with the compromise proposal for long-term credit to New York City, as he did a few years back.

Washington nightlife has never been one of his priorities, and in fact, he stayed home and read a book instead of attending the Reagan inaugural balls. His wife, Char, bowled that night -- as she does every Tuesday.

Every day he runs three miles around the Capitol. For a while he cajoled his entire staff into running the Mall with him. Aides say he's a voluminous reader, always tearing, clipping and saving.

Lugar is also described as incredibily well-organized, although you'd never know it by his office -- what he describes as an "interior decorator's nightmare." No less than 60 photos, sketches and plaques clutter the walls -- running pictures juxtaposed with snapshots of world leaders. More than 25 paperweights blanket his desk. He files things on the floor.

At the end of an hour-long interview, interrupted by a quick run over to the Senate floor for a vote, he is asked about his own personal ambitions.

Will he use this new, highly visible leadership post as springboard to 1600 Pennsylvania Ave., as some have suggested?

For the first time, he seems a little ill at ease.

"It's wild speculation . . . That's a long time away," he says. "I just don't have comment about that sort of thing . . . What I'm doing presently I enjoy very much . . . I think the future will just have to take care of itself.