her death to spare them from watching her deteriorate. I don't think she was a prisoner at 5 Poppies, remember she went to Paris (I believe) which is when Jason saw her at the airport. But remember, she was in a nice room, was able to lounge by the pool and had a personal masseuse, who she was having sex with. She was not a prisoner.
She was working on something in a lab for "him". She kept telling Pascal that "He would not be happy to know that you are treating me this way." Clearly there is more to the story. Maybe a twist is coming and it will be revealed that she was taken, but from what we know so far--she left on her own accord by faking her death.