I have a theory on Raava and Vaatu. The north and south poles represent their sphere of influence, the north, Vaatu, the south, Raava. I will grant their influence is not absolute, but if you take into account the entirety of the series (ATLA, The Search, The Promise, LOK, etc), alot of the baddies come from the Northern Hemisphere, (Yakone, Tarrlock, Amon, Unalaq, [NWT], Ozai, Koh [he stole the faces of both Ummi and Rafa-guess where? in the NWT] Sozin, Long Feng, and the list goes on) while the good guys are from the southern hemisphere (Korra obviously, Aang [born in the SOUTHERN Air Temple, then drifted in an Iceberg which coincidentally ended up near the South Pole], Katara, Toph [from Gaoling, southern tip of the EK]). The Bad outweighs the good, but that's because of the circumstances of the plot, 100 year war in Aang's time, lack of spirituality in Korra's time. What do you guys think?