More feared than loved in family fable, the stepfather in the American home of the 1990s is winning new respect for performing a role for which there is no script and the moments of applause and limelight are few. "Being a stepfather, especially if there are teen-agers in the house, is probably one of the most humiliating and difficult tasks a man can take on," said Thomas Seibt, a marriage and family therapist in Los Angeles. He is also one of 13-million stepfathers in the country.
It can be one of the most satisfying tasks. The only essential skills, it seems, are the wisdom of Solomon and the patience of Job.
"It is starting to sink in that the flexible guy who approaches stepfamily life without the intention of re-creating a nuclear family, but a functional group whatever form it takes, is some kind of hero," said Dr. Larry Ganong, a stepfather.
He is a professor at the University of Missouri who, with his wife, Dr. Marilyn Coleman, has extensively studied stepfamilies.
From their studies, Ganong concludes that "the stepfather-child relationship is perhaps the best predictor of a stepfamily's success and can make or break a second marriage."
Because women usually win custody of children in divorce cases, their new husbands must adapt to living with someone else's children.
If they are adolescents _ in a rebellious time of life that can unnerve natural parents _ the challenge can be overwhelming and quickly sour the new marriage.
As stepfather of a 12-year-old boy and a 15-year-old girl, a store owner in Paramus, N.J., had fantasies that his second marriage would be perfect; he was now "smart enough" to avoid the mistakes that ended his first.
The 40-year-old man, who requested anonymity, was comfortable enough financially to take time off from his store, spend it with his stepchildren and make a good start.
"Let's go camping this weekend, let's go to a movie, let's play Monopoly, I tell them," he said.
"But all I get in return are these drop-dead looks, and they go running off to their father's house and tell him I pick my teeth after dinner or that my own kids who visit us on weekends are dorks."
Conflicts over territoriality and discipline, especially with teen-agers, are part of the reason that second marriages fail at an even greater rate than first marriages; that children in stepfamilies drop out of school more than children in single-parent households do; and that many experts worry what kind of parents the angry, hurt children will become.
Stepfathers who overcome anger, frustration and loss of face in these confrontations are often those whose new marriages succeed.
It takes precise navigation in largely uncharted waters. Advice books are usually not read until a crisis develops and egos are already raw, researchers report.
"Everyone who gets married and starts a family has a general idea of how mothers and fathers are supposed to behave, but when you ask them about stepparents, all you get is shrugged shoulders," said Dr. Lawrence Kurdek, a professor of psychology at Wright State University in Dayton, Ohio, who studies stepfamilies.
The stepparent has few role models on television and in movies.
Stepfathers are infrequently portrayed and when they are, as in the 1970s series The Brady Bunch, little distinction is made between them and biological fathers.
Or the script imbues them with the characteristics of storybook stepmothers: cold, emotionally distant, malevolent.
Dr. Benjamin Spock was humbled by the stepparenting quagmire after marrying a woman with a 10-year-old daughter.
"Being a stepfather was the most painful experience in my life, and it was obviously even more painful for my stepdaughter," he said in a talk last year.
He said he had rewritten a section on stepparenting on the basis of his experience chronicled in his book Baby and Child Care.
Some live-in stepfathers feel like distant, unwanted relations overstaying their visits.
Dr. Neil M. Kalter, director of the Center for the Child and Family at the University of Michigan and author of Growing Up With Divorce (the Free Press, MacMillan Inc., 1990), recounts this story:
"I can't stand it," a 15-year-old Michigan girl sobs to her mother. "I have to put on my bathrobe at 10 o'clock at night in my own house to go downstairs to get an apple from the refrigerator because he's there in our living room."
Researchers and clinicians generally agree that young children, with greater physical and emotional dependence on adults, may quickly accept a stepfather's help and discipline.
Teen-agers are preoccupied with changing sexuality, schoolwork, friends and sports and are straining to break free of adult authority.
They choose to adhere to parental discipline only out of fear, or love and respect, to which the stepfather initially has no claim. He may never have.
The New Jersey businessman still flinches when he recalls his stepson's whiny reaction when he was told he should not watch an R-rated cable movie: "My dad lets me watch 'em. And besides, it's Mom's television set."
"I don't know how I made it through that first year without killing that kid," the man said.
The children's hostility troubled him until he accepted this: Teen-agers are reluctant to spend free time with their natural parents, much less an interloper.
"In the beginning of a remarriage, stepdads should be like polite strangers in their new wife's home and talk to the teen-age kids, but not intervene or exercise too much control over their lives," said E. Mavis Hetherington, a University of Virginia psychologist who has tracked stepfamilies over years.
"There's too much hostility in the kids who at that age want independence, not control."
Faced with conflict, some stepfathers overreact and disengage from the children.
""I married you, not your kid,' they tell their wives, and leave all the problems to her," Dr. Hetherington said.
She recommends being "the authoritative parent," a person high in warmth, responsiveness and communication, who monitors children's activities without demanding unquestioning obedience.
Compounding the stepfather's problems are the mixed messages he receives from the legal system and from society in general.
Many stepfathers provide full financial support for their new wives' children but have few legal rights unless they adopt them, but adoption is impossible in most states unless the natural father consents.
A natural father, in fact, retains greater legal rights to minors even if he disappears and leaves their rearing and education to the stepfather.
David Chambers, a law professor at the University of Michigan, cites the case of a Michigan man whose wife died after three years of marriage.
The widower petitioned the courts for custody of his three stepchildren, then age 4, 6 and 11; the court awarded custody to the biological father, who had provided no child support and had had little contact with the children for most of their lives.
Social conditioning can lead both partners in a second marriage into the trap of believing men are providers who set and enforce family rules _ an antique proposition even for a first marriage; for stepfamilies, it is a prescription for disaster.
"The stepfather, in his own mind, is the knight on the white horse who is going to rescue his new bride from the drudgery of single parenting and shape up her unruly kids who don't help around the house and talk back to her," Kalter said.
"At the same time, she may feel he's coming down too hard and inserts herself in the middle of the conflict and say he should back off," he said.
"Now he feels double-crossed by her, and they have marital tensions as well as parenting tensions."
Advice to play a secondary role in discipline goes down hard with many men.
For Hector V. Lino Jr., a teacher who lives in Brooklyn, it also flies in the face of his social reality.
"It's not possible for me to do that, no matter how high my level of frustration and impotence at times," said Lino, whose stepson is now 20. "It has to do with how I was raised and the realities of black children in this society."
He said the youth does not have a single friend in their neighborhood with a father or stepfather living at home to provide direction.
"I have to assert myself," Lino said. "There's no way I'm going to take a secondary role."
Whatever role a stepfather takes, issues with the children must be resolved or the marriage will quickly falter, said Constance Ahrons, a professor at the University of Southern California who is a family therapist and author of Divorced Families (W.W. Norton, 1989).
"If the relationship with the kids doesn't work," Dr. Ahrons said, "the marriage isn't going to work."
She told of a Wisconsin couple who began life together with five adolescents from their previous marriages:
"After a year they couldn't handle it. They separated but didn't divorce, planning to live together again after the last of the teen-agers leaves home."
If the stepfather has raised children of his own, the jolts of dealing with someone else's children are not so staggering.
"I'm seeing more and more stepfathers in their 30s who've never married before and take on the responsibility of an instant family," said Seibt, the Los Angeles therapist. "They are absolutely at a loss about what to do."
Seibt, 51, speaks from experience. He married a divorced woman with five children in 1977 when he was in his late 30s. "Up until then you could say I was a confirmed bachelor," he said.
For 12 years before his marriage he was a Roman Catholic priest.