“Usher” explores a family so bizarre, so self-isolating, so removed from normalcy that their very existence has become eerie and supernatural. The bond between the featured brother and sister characters is intense and inexplicable – possibly it’s supernatural, possibly it’s incestuous. Their bond transcends even death. One interpretation of the tale is that the siblings are actually one person split in two; thus one is unable to survive without the other.
Poe implies that Roderick and Madeline share an incestuous relationship.
Poe implies that Roderick and Madeline's relationship is primarily psychological and spiritual, not incestuous.