Incest?
I felt like there was some subtext hinting at an incestuous relationship between the two siblings... the only overt thing I can recall is when Linda tries to kiss him in that underground room with all the blue & purple lights (when she's on Ecstasy, I think), but other than that she's just ... very open with her sexuality around him. I don't have a brother so I don't know what it's like, and I'm sure some people would say "with a sibling that's just not something you ever think of", but personally, even if I were a stripper, I would keep covered up around my brother - not to mention the fact that she was always sort of ... leaning in toward him.
Or am I imagining all of this?
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"What would you do if someone actually understood you? You'd have to change everything."