There's a lassitude and passivity to Helga, a sense of her as captive and possession, that is depressing. She seems to have no life outside her role as Wyeth's model and, since the artist avoids most suggestions of narrative, she's a storybook character without a story.
For the most part she is there as a beautiful object: Wyeth lavishes endless attention on the strands of her strawberry blond hair, for example; it seems to be one of his favorite things to paint. Only occasionally does he allow her to look at the viewer. Usually her eyes are averted; she sleeps, stares glumly off into space or simply turns her back.
This tactic is especially clear in Black Velvet, which floats an image of the reclining Helga, nude except for a black ribbon around her neck, on a dark field. The image reprises Manet's controversial masterpiece Olympia, except that Manet's reclining nude is fully alert and stares directly... (http://www.nytimes.com/1989/06/23/arts/wyeth-s-helga-alone-and-floating.html)