Rosalynn Carter teases her that it is the smallest town she has ever seen, outside of Plains. Actually, it is smaller than Plains and though its name is Star Town, it is less a town than a crossroads with a couple of stores, a gas station and, at most, 150 inhabitants scattered there and on farms around the neighboring North Carolina countryside. Her father still lives among them.

"You won't believe it," says Madeline Fry MacBean, who as Roslyn Carter's $40,000-a-year personal assistant is about as close to her as any mortal other than Jimmy Carter can be, "but peanuts - and sweet potatoes - were his major crops."

You do believe it, though. After six years together, ever since Jimmy's move into big-time politics, there can be little doubt that Rosalynn Carter and she are of similar cloth. She feels protective of her - "like anybody you feel close to." And she is aware of complaints that she is too protective. "Protector," MacBean frames the word, then quite candidly admits that she is. "In every way."

She long ago learned to anticipate - "you anticipate what would make things easier for her without having to ask" - and she watches Rosalynn Carter carefully.

From the shadows behind a receiving line. From a doorway. From the sidelines generally, chain-smoking and alone, and usually unrecognized.

It is not surprising to learn that like Roslynn Carter's childhood, Madeline MacBean's had been cut short by family tragedy and it had fallen to her to do the cooking, the washing, the cleaning - all the chores the only girl in the family would have been expected to do on a farm when the farmer's wife had gone away.

Rosalynn Smith was 13 when her father died, and she took charge of the house and three smaller children so their mother could work to support them.

Madeline Fry was 10 when her mother home. There had been grandmothers living on either side then and an aunt who had helped out the first couple of years, but by the time she was 12 she had taken over the household chores. "We were very poor, we couldn't afford to have any housekeeping help, anything like that, so I did everything."

Outside, in the fields, George Fry and his young son Harold did everything. "We always figured," a Star Town neighbor says now, "that George worked so hard he never had time for her mother."

Growing up without a mother had one effect," MacBean supposes, "but I haven't analyzed it or tried to figured it out." "She really seemed able to understand her mothers' leaving and her staying with her father," says a girlhood chum.

Says an Atlanta friend: "Somebody turned her into a very fine girl - I think it may have been Madeline."

Whatever caused George Fry's marriage to break up, his relationship with his children earned him only respect from people who knew him in those days. Described as a mild-mannered, reticent man whose German ancestors had moved from Pennsylvania in the mid-18th century to settle around Newton, he was "so typical of the South," says an acquaintance - "Good breeding but, well, you know, poor." Friends remember a determination that his own adversities should not shortchange his children. Whenever a symphony or concert was in town, he took them, then waited outside for them until it was over. "He wanted them to have opportunities," says a Newton friend.

Whether the "opportunities" fostered the interest, or simply sustained it, Madeline Fry grew up intending to be a concert pianist. Altogether she studied piano for 10 years, through elementary and high school newspaper, the year book, played basketball, was a cheerleader, read voraciously and studied uncompromisingly to become valedictorian upon graduation in 1957. "I had so many things going," she says now, "that I lost interest in piano. I didn't have time to pratice."

"She was always different, always bright and ambitious," says a girl friend who remembers tht MacBean was popular with the boys, too. There had been one boy in particular by the end of school and "she cared about him a lot, but she also had a lot of vision and no desire to stay in Catawba County. He had no plans to go anyplace. As far as I know, he's right there now."

At first, Madeline Fry got only as far as Charlotte, about 50 miles distant, but once there she was to establish a pattern that would serve her extraordinarily well throughout the next 20 years.

"She always worked her way up to a good position," says a friend, and began by working her way up from stenographer to assistant to the personnel manager of a bank. There had been a year at Queen's Evening College (Rosalynn Carter had had a year at Americus Junior College) and some special piano studies as what she call an "out-student" at Lenoir Rhyne College in nearby Hickory. But money was always a factor - "I hated it so that she couldn't stay in college because of financial reasons," says a former teacher - and piano and any hopes of a formal education fell by the wayside once and for all when she was 22. Then, determined to see more of the world than North Carolina, she signed on with Delta Airlines as a stewardess and moved to Atlanta.

She still plays the piano but usually when no one is listening. When she thought no one was around, she liked to play the magnificient ballroom grand in the Governor's Mansion at Atlanta. One day when Jimmy Carter was around - he's just came in and listened, but of course I couldn't play anymore at all. It just made me nervous because I don't feel I play well any more." 'A Magic Mind'

Jimmy Carter's aunt, Emily Dolvin ("Aunt Sissy") of Roswell, Ga. says that Madeline MacBean can say "'no', more beautifully" than anybody she's ever known. "You don't even know it until you've hung up."

It was Aunt Sissy, in fact, who found MacBean for Rosalynn Carter after Jimmy was elected governor in 1970. Roslynn was looking for a social secretary so Aunt Sissy asked a niece if she could think of anyone who was "really efficient and didn't lose her cool." Elsie Moses knew just the person.

"She had lots of class, was experienced, worked hard and didn't keep routine hours," says Moses, an Atlanta advertising executive, of MacBean, whom she has known since the mid-1960s. By then she had left the airlines (working her way up from stewardess to hiring other stewardesses and modeling for photographs in Delta's brochures) to work in the Georgia Department of Industry and Trade. A former boss, William Hardman, credits her with helping to build up the state's fledgling tourist industry and calls her "one of the smartest people I've ever known - just brilliant with a magic mind."

From state government MacBean joined a land developing firm, becoming administrative assistant (in charge of training model home hostesses, for one thing) to the vice president of marketing. Moses remembers it was a "hard job," working for a boss who was another "real achiever - achiever, you know require a great deal of those at their right hand."

Married in the meantime to Neville MacBean, a talented young Atlanta architect from an aristocratic old Southern family she was "ready for a change" when Moses reached her in Florida that January day in 1971. The couple was spending a few days with his parents in Palm Beach and MacBean cut short her stay to fly back to Atlanta.

She remembers being surprised that Georgia's First Lady-to-be was "so young and attractive and down to earth. I walked in, naturally I was scared to death, and I didn't see anybody who looked like the could be a governor's wife. Then she came forward and just said 'Hi, I'm Rosalynn Carter.'"

Years later, Roselynn Carter would say of that earlier campaign which won Jimmy Carter the state house that she doubted she ever thought about what she would do once he was elected.

"I really got involved in the social life of Atlanta," according to Rosalynn Carter, "but we entertained foreign ambassadors sometimes . . . and we would have 250 people in three nights a week, about six or seven weeks, so Jimmy could explain to people what he was doing."

The Carters, for the most part, "just worked, and we had our friends," says MacBean. "They would come in on occasion to be with us and we went to the symphony because it needed some encouragement. But most of the things we did were working."

MacBean could understand that better than most, and friends remember that in no time at all she was more than a social secretary keeping 9-5 hours. She was but a confidante and family companion as well.

Of the relationship, MacBean says only that "when you work right in the house everyday with a family, you get to know them very well." In the process she and Rosalynn "just became friends . . . I consider her to be one of my best friends." Fashion, Not Fad

In the White House East Wing suite once occupied by Betty Ford's social staff, Roselynn Carter's office connects with two smaller ones. MacBean has one, the other is occupied by Carol Benefied, a campaign volunteer who came up from Atlanta to be the First Lady's administrative assistant.

At the far end of the hall are the offices of others on Rosalynn Carter's 18-member staff. All deal with the different aspects of hers and the family's public side Madeline MacBean's domain is the personal or private side.

As she spells them out, her concerns are Rosalynn's friends who come to visit, overnight houseguests, private entertaining, operation of the household Rosalynn's personal commitments - and Amy.

She claims that she plays "no major role in overseeing arrangements for the Carters' private social life, yet she is as attentive as any hostees when guests begin to arrive. The President's series of small dinners for members of Congress moved into MacBean's domain once dates were agreed upon and invitations issued by Frank Moore's Congressional liasion office.

"My responsibility is the second (family) floor," she says by way of definition. "Gretchen Poston's (the White House osical Secretary) is the first (state) floor."

"We do a lot," she says of theater and bowling parties she arranges for Amy Carter, the picnics (one recently for children of the family's Secret Service detail), Saturday afternoon concert outings and weekend trips with young friends to the country. "She must be having fun."

She knows Rosalynn Carter's needs, aspirations, tastes, moods, desires and habits and has shopped for her so long that there is no hesitation if she spots shoes she knows Rosalynn needs. Arraangements for the First Lady's recent buying trip to New York were handled by MacBean, so discreetly, in fact, that neither White House staff nor press corps was aware of it until it was over.

Petite (5-feet-3) with a slender figure and a preference for what's fashionable but not faddish, she surveyed designers' showrooms with her own needs in mind once Rosalynn Carter's had been established. "She's got a nice fashion sense for her own figure," says designer Dominic Rompollo, impressed with her all-business demeanor. "We don't mince words."

She still calls Rosalynn Carter "Rosalynn" but tries not to do it now in public, just as she doesn't call Jimmy Carter "Jimmy " in public anymore.

It is an easy familiarity that is as natural by now as it is instinctive. "We've had the same kind unbringing, the same kind of background so I'm sure we think alike," she says. Even so, there have been disagreements ("but if I remembered about what I probably wouldn't talk about it").

"I've always tried to honestly express how I feel about something. I don't tell her what she wants to hear, or agree with her just to agree with her." Getting Settled

Madeline and Neville MacBean have lived here three months now and unlike some with proximity to power, have managed to escape the social lionization which is Washington's other game.

("If I lost my job tomorrow," Eleanor Roosevelt's personal assistant/companion secretary once said, explaining why she never accepted social invitations throughout her White House tenture, "those people wouldn't give me house room. And anyway," Malvina "Tommy" Thompson added, "you're always expected to pay for such favors - in some way.")

There have been invitations,of course, but MacBean has "regretted" more often than she has accepted, pleading with only the softest trace of a Southern accent that it has taken time to get settled. Professionally, with the Carters at the White House, and domestically, in a Georgetown apartment with Buzz (the cat) and Neville, who never htsitated an instant about leaving his Atlanta architectural firm in order to accompany her to Washington - "I've never had any problems along those lines," she says.

Much as Rosalynn and Jimmy Carter "just worked . . . and had our friends, a small dinner party, a symphony, a ballet, some cultural exhibit over a big party anytime.

"I can't imagine Madeline ever being intimidated by anyone in the Washington power structure," says a friend.

One wintry day last November, a reporter for The Observer-News-Enterprise of Newton, N.C., drove out to hopes of borrowing a photograph of his daughter, by then unquestionably the community's most famous citizen. He didn't have one, Sylvia Ray said later, except with some family friends. She assured him that would be all right because she could always have the darkroom technicians crop out everybody except Madeline MacBean.

The Observer-News-Enterprise decided later, however, to leave the photograph alone. The "family friends" were Rosalynn and Jimmy Carter.