No man but a blockhead ever wrote except for money.

Samuel Johnson's comment, made more than 200 years ago, is fondly quoted by a latter-day literary pragmatist named Michael Fain. In fact, Fain, 49, might even add that no woman—or for that matter, no couple—would write without money in mind. To that end, he and his wife, Judith Barnard, 52, have teamed up for publishable profit under the pseudonym Judith Michael. The Chicago writing team's first novel, Deceptions, was a best-seller in 1982. Their latest, Possessions (Poseidon Press, $16.95), has followed the same path. Both books are based on an adage that old lexicographer Johnson might not have subscribed to: Everybody needs a fantasy.

In Deceptions twins trade places for a week to look at their lives from a distance; then, because of an accident, they can't trade back. In Possessions a rather plain Vancouver housewife wakes up one morning to find that her businessman husband has mysteriously departed. She soon learns that he had disguised his name and background and that she had unknowingly married into one of San Francisco's wealthiest families.

The Barnard-Fain brand of fantasy has even hooked the competition. "They have a unique style," says best-selling romance writer Janet (The Hostage Bride) Dailey, who admires the authors for not simply repeating their successful plot lines.

Working in their four-bedroom Chicago apartment, the pair spends days or even a week scripting the first draft of each chapter and refining dialogue and plot. Then Judith, the more intense and compulsive of the two, writes the first version on her word processor, and Michael makes notes for the next one on his processor. They pass the chapter back and forth until Michael, at least, is pleased with it. "Judith is never fully satisfied," says her more easygoing spouse. "If I didn't put my foot down, she'd still be doing revisions on the plane on our way to our publisher in New York."

The collaboration has been going on since 1979, the year they were married. Back then Fain, who attended the University of Chicago and later did technical writing in his career as an optical engineer, was working for a women's sportswear chain. Barnard, a Northwestern alumna, was free-lancing textbooks, educational films and magazine articles. At Barnard's suggestion they co-wrote a few magazine articles on such subjects as marriage, family and travel. Then the two, figuring the money was in books, decided to try a novel. The pair eventually spun out three chapters of Deceptions and, via their agent, sent them off to a publisher.

Simon and Schuster smelled a winner and quickly offered them a contract. The authors pressed on, meticulously researching details of the English and American settings of Deceptions. Unlike many first-time novelists, they avoided reading the competition in order to develop their own, nonderivative style.

On the domestic front the collaboration has its drawbacks as well as rewards. "We sometimes find ourselves living in a hothouse, with no place to escape," says Fain. Judith copes by spending money (buying herself a sweater or expensive scotch for Michael) or, when she is really desperate, by cleaning the oven. Michael, an expert photographer, retreats to his darkroom or attacks his exercise bicycle.

Thankfully, each emerges from these battles a winner. Both Barnard and Fain grew up poor, but now own a co-op apartment probably worth a quarter of a million dollars. Their income is healthy enough to support Judith's therapeutic shopping sprees and peace offerings of pricey, imported raspberry-filled chocolates.

Given their success, one head must always remain relatively cool in their domestic skirmishes, which have so far remained short-lived. During one literary fight Michael jumped up and declared, "That's it! I'm leaving!"

His partner eyed him calmly. "You can't," replied Judith. "We have a contract."