Neptune is 30 AU from the Sun, while Sedna is 76 to 976 AU!! From a spiritual stand point, compare Neptune with (90377) Sedna is like compare Earth with Heaven.
In the original myth, Sedna is related to birds (Venus quality) and dogs (Moon quality), and also to cold water (serene and calm feelings) and is opposite to the human nature (academic intelligence).
The people that I met with (90377) Sedna prominent in its chart reminds me, Koda, the pure heart little bear of the Disney movie "Brother Bear" (2003), they also remind me the high emotional intuition of dolphins (spiritual intelligence).
(90377) Sedna has a feminine yin receptive component in its nature, she tries to link up to the elements of its environment. It is very different to the masculine force of Neptune, that tune with the unconscious components of the environment and tries to reinforce them by reflecting back its quality. Neptune has a strong yang inductive force like the three laughing masters (the last card of Osho Transformation Tarot).
