Something has happened to our Georgia peach, Henriette Allais, since we first saw her. That was in March 1980, in the centerfold of our favorite magazine. As Miss March, she conjured up visions of Scarlett O'Hara: fiery, sensuous, with more than a hint of Dixie in her voice. But that was two years ago. When we saw her again recently, there were changes. The fire and sensuousness remained, but there was more strength, more self-assurance, more vision. The accent had taken on a definite foreign tone that gave a clue to her transformation. For the past year and a half, Henriette has worked, played and grown in Paris. She chucked everything for the modeling game and leaped in headfirst. Paris welcomed her with open arms. Before long, Henriette was one of the busiest models in the City of Light. That's no mean feat; the number of girls trying to make it there is legion. But if, like Henriette, you're chosen, there's nowhere to go but up. "Paris is the best place to get a good portfolio together," she declares. "The competition is very stiff. About 60 percent of the models are American girls. The French photographers like them because they are big and tall. The reason I've been so successful is that they can't categorize my look. It's so changeable. I can go from totally innocent to totally sophisticated to totally sexy." A girl who can convey sexiness with her body is gold in Paris, whether she's on the runway or featured in product ads, fashion or creative photography. For the French audience, inhibition is out and libido is in. "I've seen some of the most beautiful and sensuous commercials ever on prime-time television," Henriette says. "If you go for an audition, it's common to be asked if you mind showing your breasts." The Gallic penchant for the erotic is quite all right with Henriette. "I don't feel at all inhibited about being sexy," she says. "There are many good photographers in the U. S., but they are limited in what they can shoot. They get locked into formulas. And, after all, it's 1982. Women have got to stop the cheesecake and start being more seductive." What's the difference? "It's mostly in the eyes," Henriette says. "For instance, I like to laugh, but not when I'm trying to seduce someone. To get the proper look, you have to use your eyes, actually talk with them." Being a sought-after model can play havoc with one's private life, but Henriette has it under control. "When I left the South, I found that things were very different in the big cities, where people ask you how much money you have and what kind of car you drive. I don't care about that stuff. I could be a millionairess by now with all the offers I've gotten. People want you to go with them on their yachts or to be their mistress. I turn them down because I don't want to be held down. Even in my marriage, I don't like that. If my husband feels he has to get away, he goes, and the same for me. It took me a long time to get out of the trap of being in love with someone and thinking he had to be there all the time. You just can't own another person. It's not fair. It's not human."