Although David A. Clarke will not be sworn in as chairman of the D.C. City Council until noon today, the tangible transfer of power was marked by two events last week--events that also offered clues to the nature of this towering, complex man who becomes one of the city's top elected officials.

On Wednesday, Clarke sat down for an early morning chat with Mayor Marion Barry, D.C. Del. Walter Fauntroy and school board President David Eaton at what is to be a weekly, off-the-record "fellowship" meeting among top leaders. Clarke, 39, had known and worked with them all since their civil rights days back to 1965.

Clarke retains not only the politics but the fervor of those civil rights struggles, and is intensely committed to his ideals. But now he enters a job in which the major task is building consensus, and some in the District Building question his ability to bend when flexibility is required.

Clarke, 6 foot 5 inches and 250 pounds, spent the rest of the day pitching in with sweating aides and movers who were lugging heavy boxes of books and personal memorabilia down the hall from his Ward 1 council offices in the District Building to the ornate and spacious corner suite reserved for the chairman. There was no need for the chairman-elect of the council to help move his own files. But Clarke has always seemed uninterested in the trappings and perks of office. He has never been a stylish dresser, he rarely stands on ceremony, and he is stubbornly blunt.

Clarke's critics describe him as self-righteous, quick-tempered, arrogant. His own staff acknowledges that the stern presence and harsh rhetoric he often displayed during his eight years representing the inner-city Ward 1 on the council accurately reflected the flash of his temper.

"I know I'm not easy to work for," he said recently. Asked about the need to moderate such tendencies as chairman, Clarke responded, "That's going to be the hard part."

As for the trappings of office, Clarke is trying to give up his rumpled look for neater haircuts and new suits. But he resisted the suggestion of some council members that it would be more fitting for a chairman to get around by car instead of bicycle--his favored mode of transportation--and he remains suspicious of the perquisites that some other politicians covet.

"The reason politicians need perks," he said, "is because their egos are always under attack so much they have to build them back up."

Clarke haltingly began his bid for his new job earlier this year as the distant underdog to incumbent Arrington Dixon and former council chairman Sterling Tucker.

Clarke unexpectedly announced in April that he would not run, partially because he feared "growing racial distrust" that he said was exacerbated by the policies of the Reagan administration. Clarke is white; Dixon and Tucker are black.

Two weeks later, though, he changed his mind, saying supporters urged him not to bow to racial tensions. His friends praised him while some critics viewed the episode as a crafty way to appeal for black support in a city 70 percent black.

Clarke campaigned aggressively, calling on a grass-roots coalition of labor, consumer, housing and civil rights groups to bolster his low-budget, $100,000 campaign. He trailed badly in early polls, but won key endorsements--and indirect encouragement from the Barry administration, which could have thrown roadblocks in his path. He emerged with just under 50 percent of the vote on primary day, and faced no Republican opponent in the general election.

Clarke has met several times recently with the 12 other council members, proposing new committee assignments and a reorganization. In one 90-minute session, he simply had the council members describe their feelings toward one another.

But while he has won high marks from colleagues for consulting them, which they say Dixon rarely did, some council members nevertheless remain skeptical of Clarke's ability to lead the often fractious body that nettled Dixon endlessly.

"Consensus building is taking a lot longer than I thought it would," Clarke said in an interview last week when asked how his perception of the job had changed since his election.

"I'm a political infighter trying to get rid of the infighting. I recognize now how deep-seated the competition is. But I'm also finding a good desire on the part of the people to work together."

Clarke, whose father died during World War II, moved to Washington at age 2 with his mother. He attended Thompson Elementary and later Jefferson Junior High in Southwest Washington. "Not the Southwest that's there now," Clarke recalled. "Before urban renewal, when there were communities . . . . "

When Clarke was 16, his mother died of cancer and he moved in with his aunt and cousin at 12th and M streets Northwest. "He's always been a high-minded type," says cousin Jay Cone, now a medical supply dealer in the Cleveland area.

With his wife Carol, a city school teacher, Clarke lives in a rambling house in Mount Pleasant, has one child and guards his privacy. Asked about his parents, he says simply, "there's no public reason to know," although he readily talks about other aspects of his life.

He likes to buy antiques and oriental rugs from a downtown auction house, and tries to do restoration on his home. Asked to name his closest friends, Clarke says politicians have a hard time knowing who real friends are. Rich Siegel, a friend who is going to work with him, agreed to do so only after he and Clarke talked about the dangers of damaging their relationship.

Clarke says he remains close to Stoney Cooks, a friend from the civil rights battles who is Atlanta Mayor Andrew Young's closest adviser. He also names as a friend Jerry Cooper, a Washington political and social fixture who serves on the lottery board.

Clarke went to Western High School and describes himself as an ordinary student until his graduation in 1961. "I didn't do much extracurricular," Clarke said, adding that he did coach the baseball team.

He went to George Washington University to study religion, hoping to become a Baptist minister. Instead, in the mid-'60s, already active in the civil rights struggles, he decided to become a lawyer and enrolled at Howard University Law School. One lasting effect of his religion and law background is an oratorical style that sometimes awkwardly combines the poetic rhythm of the minister's message with the polysyllabic density of a lawyer's brief.

As a law student at Howard, Clarke became involved in the Free D.C. Movement to gain home rule for the city and also worked as a legal aide to the Washington office of the Southern Christian Leadership Conference. It was in those years that he met Marion Barry, who had come to Washington in 1965 to raise money for the Student Non-Violent Coordinating Committee. Clarke says his mentor was the late Frank D. Reeves, a longtime civil rights activist associated with Howard Law School for more than 30 years until his death in 1973.

Clarke remained active in local and national civil rights matters. In 1974, he ran for the City Council--the first time members were elected rather than appointed--and won, drawing on the strength of his involvement in community, civil rights and housing affairs around Mount Pleasant, Shaw and Adams Morgan.

He easily won reelection in 1978, defeating a field of candidates, including Frank Smith, another colleague from civil rights days who went on to become the school board representative from Ward 1 and this year won Clarke's vacated council seat.