Am I the only one...? (spoilers)
Lettie obviously had very strong feelings for her brother, and it's subtly (and sometimes not-so-subtly!) implied that her feelings were perhaps bordering on incestuous. At the very least, they're not healthy feelings.
However at some points in the movie I got the vibe that Harry somewhat returned her feelings. Was it just me??? I think I felt it most when he wrote the letter admitting his guilt and tried to get her freed from prison. Throughout that scene I just got the feeling that Lettie had a strange hold over Harry that wasn't natural. When he grabbed her and turned her around to face him I honestly thought they might kiss!!!
I know that that part of the film was "all just a dream", which makes me wonder even more, because all the intensity during those scenes was only happening in Harry's mind!