I like Fern as well, but the more I think about it, the more I see her a rather oppressed character... not so much in a literal sense, but rather like when she has the opportunity, not only is there a passive aggressive streak that surfaces like Drtooth mention, but there also seems to be a bit of an over-confident, and somewhat egotistical streak that can shine through as well, and it's like when those streaks shine through, it takes a while for her to be snapped back to reality.