I agree there. She's always an outsider where ever she is at. Each story paints her as an outsider for various reasons, her mortality, her beauty (?), perhaps sexuality, her strength or weakness if you consider mortality vs immortality. Yet she is also always a person of strength though it is in a liminal sense in that it is both on the fringe of the social order and placed in a uncivilized place or perspective. Figure in the Poseidon rape story she is found on the edge of the known world and in some association with the entrance to the underworld. If I recall correctly Perseus had to use Charon to get to the Isle of the Dead to actually face her. In the three sisters mythos she is placed on the fringe of the known world and towards the Black Sea area moving towards Anatolia (modern Turkey). Which I believe is where the two stories merge in that both take place on an Isle of the dead type location. But very much the foreign or uncivilized lands and peoples to Hellene perspective.

The story gets sort of strange when compared to the masculine feminine attributes of Athena that were pushed later when you consider her non female birth. So her rape gets seen in the light of Artemis type scenario more so than a betrayal due to seduction and rape. Yet it's more about a failure of her masculine feminine than her feminine feminine which sort of equates to her being punished for not being a manly woman vice being a womanly woman. So she is punished I suppose for being more focused and pushing the feminine and female than for being the warrior I suppose like an Amazon. The idea of hair transformed into snakes seems to suggest cursing that which was held in vanity and pride type thing as an attraction. A snake body could be seen in the same light I suppose. A body in some accounts like Echidna's (snake lower torso and human upper torso) other depictions more like a Naga in that most of her body was serpent or snake like and only a little bit of the upper body human like with two arms, upper torso head.