"If Thomas Covenant can have hope, anybody can have hope, for God's sake," says Covenant's creator, Stephen R. Donaldson, trying to explain the phenomenal popularity of the leper hero of his best-selling fantasy, The One Tree (Del Rey/Ballantine, $14.50). "Who leads as miserable a life as that poor fellow?"

Ten years ago hope was virtually all that sustained Donaldson himself, who told neighbors around the Sewell, N.J. farm where he then lived that he was an editorial assistant, or a house painter—anything to avoid admitting that he was a writer who could not sell his work. He had sent the first three of his bulky Covenant manuscripts out to every major publisher in the U.S. he could think of, and one by one the rejections, 47 in all, had come back. Rather than give up, Donaldson dove deeper into his fantasies. He recalls his wife, a social worker who supported them both, coming home and asking, "What are you thinking about?" "I'd say, 'Thomas Covenant.' She wanted me to be thinking of her." Their 10-year marriage ended in divorce.

Soon after, however, Covenant and Donaldson began to thrive, and today the writer leans back in his recliner, exhales a rich cloud of smoke from custom-blended cavendish and latakia pipe tobacco, and says wryly, "This is my famous-author chair. I bought it after I won the British Fantasy Society award for the first trilogy in 1978."

Donaldson, at 35, is now world-famous, with an income he sheepishly puts at "a comfortable six figures" and a lovely second wife, Stephanie, 25. They met after she rose to make a comment on the meaning of wolves in fiction at an Albuquerque "con," as sci-fi fans call their conferences. Donaldson, a panelist, remembers, "I was very conscious of Stephanie. I elbowed the moderator to get him to call on her." After the session Donaldson gave her an autographed copy of his first book, Lord Foul's Bane. Stephanie, who come August will be a teaching assistant in English lit at the University of New Mexico, says, "I was afraid I'd hate it, but it was just fantastic. I could tell him how wonderful it was with a clear conscience." After their first lunch, Stephanie "immediately canceled all my plans." They were wed in 1980 and bought a suburban Albuquerque home.

Stephen's story-telling goes back to his childhood in India, where his Presbyterian medical missionary father was chief of orthopedics at a 900-bed hospital in Miraj and his mother was a physical therapist. Mysticism and danger were a part of everyday village life—Donaldson recalls once missing school when a man-eating tiger was on the prowl—but, exciting as real life was, he dreamed up stories too. He made himself the hero of a cowboy saga at 10 and at 16 created a superhero who was mute. But being a writer did not occur to Donaldson until he got to the College of Wooster in Ohio. "In my wing of the dorm," he recalls, "we had five National Merit scholars, five professional musicians and a guy who had already written eight novels. I was the only person who didn't have something immense to offer the world." Sitting in church the first Sunday, grappling with his lack of a calling, Donaldson decided to be a writer: "Something in my mind leapt the gap between being addicted to reading stories and wanting to write them."

The novella he started that night, and all his other early efforts, came to nothing, because "I was trying to write what I was studying, things like the development of irony in the novel. It lay dead on the page." One Sunday in 1972 "the entire Covenant extravaganza blossomed" in his mind as he sat in church again, listening to his father, who was home on leave and giving a talk about how leprosy affected the psyches of his patients. Donaldson went right to work on his leper hero. "I was electrified at the way Covenant came alive," he remembers, "and I just had to get it published, or die."

The figure who emerged is one of the unlikeliest heroes in contemporary popular literature: Thomas Covenant is himself a best-selling author who detests his own work and has already lost two fingers to the ravages of his incurable disease. His wife has abandoned him, taking their son, and he keeps finding himself transported to a nether world called The Land. There he is instantly taken for one Berek Halfhand, a legendary hero who was the first to use "earth power." In the early going of the first volume, Covenant confronts "cavewights" or "evil creatures" (there's a handy glossary in the back), beholds the sinister Lord Foul and finds himself atop a 3,500-foot cliff which he must descend despite his acrophobia. Things aren't all bad: Although impotent since the onset of leprosy, Covenant manages sex with the lissome maid who rescues him.

Since Lord Foul's Bane, it's been just one awful thing after another, through four more fat books, for Tom Covenant. In the current volume, he is sailing aboard a huge vessel made of stone when he is set upon by a Raver, one of Lord Foul's three vile servants, who has assumed the form of a pack of huge, savage rats. "Covenant," the leprous adventurer snarls at himself, "you would be ridiculous if you weren't so—ridiculous."

This may indeed be simply flapdoodle fraught with moral implications, as the story's embarrassed hero suspects, but it's selling like hotcakes. Five years after publication, Lord Foul's Bane has sold 700,000 copies, and Donaldson's subsequent chronicles have each sold about 80 percent of that. The One Tree was so hungered for by Donaldson's fans that it went through two more printings within three weeks of publication day. Why is fantasy like this flourishing, at a time when the bulk of the book business is in recession? "Little kids love fairy stories, and I think grown-ups do, too," says Ballantine Books' Lester Del Rey, who in 1976 knew, six hours after he plucked it from the slush pile, that he wanted to publish Lord Foul's Bane.

What's next for America's best-loved leper? Donaldson recently finished the last book of the second trilogy, White Gold Wielder, scheduled for publication in 1983, and he has sketched out yet another trilogy which, he says, would complete the story as it flashed before him that morning in church 10 years ago. "I would like to finish it one day," he says, "but the trouble is, a trilogy is so demanding." Each one, he explains, represents four to five years work—and work is five days a week of 7:45 a.m.-to-5 p.m. concentration, "a form of Zen," in which he closets himself under the roar of classical music. Still, he's clearly hooked. "I've been away from my typewriter for about six weeks now, and I'm starting to get a little flakey," he confesses. "Writing is just too exciting not to do."