Why did Danielle Rosseau stay in the island for 18 years and know nothing about the black cloud?
Besides having some familiarity with the smoke monster, a lot of Rousseau's misinformation has been explained simply through Ben telling her to run when she heard the whispers, if she wanted Alex to live. It's not like she had a free pass to explore the island, like most of our Losties. One of the reasons she must have become to paranoid is that she is staying quiet and naive to save her daughter's/her own life.
