Dona Juana in Love : WRITTEN ON THE BODY, By Jeanette Winterson (Alfred A. Knopf: $20; 190 pp.)

“Don Juan falls seriously in love” is a short way to sum up Jeanette Winterson’s novel of quick changes and askew effects. It plays in two registers: a series of wry, near-absurdist seductions, and a lush story of passion in a tragic setting. Each register feeds occasionally into the other. A fierceness once in a while comes through the irony; a note of self-mockery is heard in the passion. Mostly, though, they are so far apart that the readers’ attention flutters about for a perch. Cello weeps and fife skirls. Each is arresting--particularly the fife--but a connecting inner line is missing.

Winterson’s narrator is her Don Juan or, rather, her Dona Juana. As we read of the affairs with Inge, Bathsheba, Jacqueline and others, and of the final grand passion for Louise, we are never told specifically that the narrator is a woman. Winterson makes a point of not telling us. And she makes an equal point, through detail after subverting detail, of leaving us in no doubt at all. It is like the Argentine card game truco , whose rules require cheating. We are cut off from our assumptions and groomed to enter Winterson’s unsettling polymorphous world.

The narrator’s voice divides registers right from the start. We hear her lavish Swinburnian recollection of Louise: “We lay on our bed in the rented room and I fed you plums the color of bruises. Nature is fecund but fickle.” Recalling country expeditions and nude swimming, it is all perfume: “We were happy to be like colts, flagrant like rabbits, dove-innocent in our pursuit of pleasure.”

Then, telling of the time before Louise, the voice turns sardonic, world-weary and often very funny. Careless about her looks--she is no beauty, it seems, and favors baggy shorts--the narrator has Don Juan’s sexual confidence. After the Spaniard got through windows and past fathers and duennas, there was no question but that the lady would succumb. The narrator is equally certain that her desire legislates. She is equally in a perpetual erotic whirl, and equally contemptuous of husbands and conventions.

She recalls some of her conquests. There was the woman who insisted on outdoors loving “with 2,000 midges as guests.” Doctors were required to remove splinters and brambles, and after they broke up, “it was pleasant to walk in the country again without seeing every bush and shrub as a possible assailant.”

There was Inge, the tender anarchist, who refused to attack the Eiffel Tower--too many lovers patronize it--but conscripted the narrator to help blow up public urinals. While Inge arranged the explosives, the narrator entered with a pistol, proclaimed the place to be a patriarchal institution, and announced to the astonished patrons: “My girlfriend has just wired up the Semtex and would you mind finishing off.”

She settles down briefly with Jacqueline, a homebody who works at the zoo, gentling “small furry animals that wouldn’t be nice to visitors.” Too much erotic dissipation leads “to the Jacquelines of this world,” the narrator reflects, but after too much domesticity, “the Jacquelines of this world lead to--”

Louise: tall, creamy, flame-haired and passionate. She is married to Elgin, a poor orthodox Jew who has worked his way up to become a rich and famous cancer specialist. Preferring computer games to conversation, he doesn’t much mind the narrator’s visits until one night when the lovemaking keeps shifting the bed in the room above. Next morning, pale and pinched, he complains that he has had no sleep. “Lives depend on my work and because of you I shall not be at my best today. You might think of yourself as a murderer.” “I might but I shan’t,” says Louise as he storms out.

So much for the high Firbankean fifing. The tone drops three octaves. Elgin, the book’s only real male presence, is a monster. After Louise and the narrator have been living together for five months, he informs the narrator that his wife has leukemia, though as yet without symptoms. She will die within eight years unless he takes her immediately to his clinic in Switzerland for the latest in experimental therapies. Knowing that Louise will never agree, the narrator forces her hand by running off to live in a hovel on the Yorkshire moors and work in a wine bar.

Before long, moved by her own suffering and the advice of the old lesbian who runs the bar, the narrator changes her mind. Louise has left the clinic and disappeared; the narrator searches hospitals, talks to lawyers, interrogates Louise’s mother and grandmother, and has a comically bloody encounter with the repulsive Elgin. The ending is ambiguous; possibly, though only provisionally, happy.

It is an affirmation, though, of the kind of freedom that Winterson devised in such previous novels as “The Passion” and “Sexing the Cherry.” It is the freedom to take whatever form one wishes, and to cast off all prescriptions: social, moral, existential, sexual and--in the writing--aesthetic and literary.

Winterson has previously made her flights through various forms of historical and ahistorical fantasy. Here she uses old-fashioned melodrama, frequently spiked. As in her previous work, a sardonic humor and an ironic sense of the absurd serve as anchor and launch pad.

But “Written On the Body” is less successful. The anchoring slips and the pad is overgrown. Occasionally, the narrator’s anguish and longing find words that make them bite. More often, though, both the anguish and the ecstasy carry great tasseled swatches of prose that end up veiling narrator, lover, passions--and all the little points of irony that pierce them--in one undifferentiated mass of purple.