read menus backwards, start ing with dessert," confides MarieI Hemingway, her coltish, rawboned frame tucked into a banquette at a Hollywood cafe. "Dessert is my main interest." With her broad cheekbones, heavy eyebrows and low forehead conspiring to make this lanky granddaughter of the great novelist Ernest Hemingway look like some unusual combination of Swede and Eskimo, 21-year-old Mariel Heming way has nonetheless managed to start the menu of life backwards, too. Sweet things like film roles with world-class di rectors and writers (Woody Allen, Bob Fosse, Robert Towne), bon-bons like an active love affair with a mucho hand some leading man (Christopher Lam bert), have already crossed her plate. Her most recent morsel, following up her praised portrayal of slain Playboy Playmate Dorothy Straiten in Star ’80, is a co-starring slot alongside Peter O'Toole and Vincent Spano in an up coming comedy-drama called Creator. In person, Hemingway is tall, speedy, giggly and not quite either the ethereally calm teenager she played in Woody Al len’s Manhattan or the world-class athlete of Robert Towne s Personal Best. Were she not a movie star, she could be the proverbial girl next door. Or, judg ing from the cuts and bruises she sports from her minor collisions with life, the tomboy next door. As Bob Fosse, her Star '80 director has said of her, “she has a kind of innocence without being dumb.” It was also Fosse who for a long time didn’t think Hem ingway had the sex or the sophistication to play a Playboy model. Fortunately he changed his mind, but meeting the real Mariel you can see what he meant. Though she is athletically attractive, she’s no classic beauty and her manners have the charm and directness of her Idaho small-town origins. Says Hemingway herself, “The other movies I’d done I was son of playing myself — I wasn’t really but it’s a great compliment when audiences think you are. Those movies weren’t different enough to show what I could do. I wanted Star '80 so badly in order to make a statement that I could do lots of A NATURAL SCRUFF MAKES OUT different stuff." She laughs and adds rue fully, “It’s real funny. Now Star '80 came out, everyone thinks that's what I can do. They never really believe you’re an ac tress, you know.” Hemingway is not only an actress, she is also, literally, “a natural.” One of three daughters of Ernest Hemingway’s son, Jack, she grew up living the outdoor life with her father, a dedicated hunter, fisherman and sports writer who taught her to fish, dry fly method. "I had no de sire to be an actress,” she recalls. “At dif ferent times I wanted to be a singer, a marine biologist, a secretary.” Margaux Hemingway, Mariel’s sister, was already a well-known model and when Margaux got her first film (Lipstick) she asked Mariel to be in it with her. "Even after that film, 1 really didn't think I'd do it again. 1 went back to Idaho to ski race — which was my passion for a long, long time. Then 1 got a TV movie playing an unwed mother. There were millions of babies around and 1 was baby crazy at the time. It was 18 days and I really worked hard and I had the best time And then I did Manhattan with Woody [Allen] and of course that was fabulous. Those two experiences decided me.” Now, Mariel says, "I love my work so much I go crazy when I'm not working." She's also made recent preliminary steps toward studying her craft. She's taken on an acting coach "when I’m not working. 1 tried acting classes but I didn't like all that Method stuff. This way, it's just me and him, and I go and read Shakespeare. Chekhov, ail the stuff I’ve never done.” She also did her first play, in Dallas, "and I want to do it again and again and again. It was so good for my voice. 1 used to be quiet. I used to hide behind my mother and everything as a kid. I was desperately shy as a teenager I used to be a nightmare for the sound people — they were always saying, can’t you speak up louder? That’s ail changing, as you can see." She Is especially happy with her new film, Creator, because "1 get to yell and scream. I’m definitely not the victim in this one " However, in the part drama, part-comedy about a scientist (Peter O'Toole) who plays God, Mariel is once again in risky sexual territory. In At an bateau she was Allen’s teenage mistress, in Personal Best an athlete involved in a graphic lesbian affair, in Star 80 a nude model and in Creator she's a college girl trying to get the much older O’Toole into bed. There’s no question Heming way’s fresh looks and inner simplicity make her effective in such roles. Her frankness extends to her own life and the May-September relationship she had with Robert Towne, the top Hollywood screenwriter who made his directing debut with Personal Best "Robert and 1 didn’t go out when we were making Personal Best — in fact, he was going out with (co-star) Patrice Donnelly. But I did live with him when 1 was making Star '80. It’s so incestuous and awful. Isn’t it fun? It never crossed my mind when we were working to