Almost at the end of Season One! Although I’m sure that nothing I’m about to say hasn’t been floating around for a while, I needed to put it all together in one place. As such, here goes my big block of hypothesizing for this season of The Legend of Korra:
Korra is not the Avatar, but is a portion of the Avatar, with Amon making up the other, spiritual side.
First let’s get the obvious clues out of the way:
1) Amon’s dodging moves are extremely similar to light-footed airbending tactics, especially the “be the leaf” moves Tenzin and his kids had tried to teach Korra. I don’t think it was a coincidence that the latter scene was presented. It could be a significant plot point that ties Amon to airbending and to Aang.
2) Although there’s still heavy debate over whether Amon’s bending-removal method is spirit/energy-bending, chakra-blocking, or advanced chi-blocking, one thing we can all agree on is that he’s a hell of a lot more spiritual than Korra is.
3) Korra cannot airbend no matter how hard she tries and is extremely out of touch with her spiritual side. Even with water, earth, and firebending, her fighting style is relatively unsophisticated, as she’s resorted to the brute, physical side. Her social skills are aggressive and blunt, and so far every fan has described her as a meathead.
4) In his stories, Amon claims to wear his mask because of a firebending attack. But it could instead be because, as a spirit, he has no face.
5) Amon has said that his powers were given to him by the spirits.
6) In Episode 8, Tarrlok seemed a bit too certain when he called Korra a half-baked Avatar who had not figured out airbending.
In the pilot, two things were immediately established about Korra:
1) She could bend the three non-air elements at an unusually young age. Unlike her Avatar predecessors who had to be told by the White Lotus councilmen that they were the Avatar, Korra’s knew of her innate abilities without such an announcement. She stated her Avatar identity to the White Lotus, not the other way around as it’d always been. There is likely an explanation behind this that is deeper than just a toddler going “I can bend three elements, of course I’m the Avatar!” After all, the ability to bend all four elements have resided in previous Avatars since their birth—they simply didn’t bother attempting to access it until they were informed of their ability…so why did Korra? What spurred her to decide to bend one element after the next, alone, so out of the blue? All of this could be a clue to untypical circumstances surrounding Aang’s death and the reincarnation phase.
2) Korra could not access or embrace her spiritual side. I believe this was heavily emphasized not just as a plot-driving source of struggle for Korra (i.e. “How will Korra save the world if she can’t even airbend? She must uncover her path and find her destiny, etc., murmur”), but as a key device in the bigger picture (i.e. What if airbending isn’t coming slow to Korra, but is in fact not within her ability at all?) What if she was never born with the spiritual side, because sometime between Aang’s death and Korra’s birth, that energy took a less traditional route?
The flashbacks/Korra’s visions have to do with Amon, not (at least not only) Tarrlok.
Aang’s warning couldn’t have been about Tarrlok’s bloodbending skills alone. Korra’s flashbacks began long before Tarrlok became a focus of the plot. Then, he was a villain subplot within a villain plot, whose quick rise and fall in two episodes does not justify a series of flashbacks that has driven most of Season One’s speculation.
Add to this, the fact that during each flashback, Amon has either been present or nearby (except when Korra was bloodbent and thrown around in the council room, but who knows, Amon seems like the type to lurk in shadows). If Amon is indeed the spiritual side of the Avatar, it’s possible that Korra’s flashbacks aren’t evidence of her spiritual progression. Rather, Amon could be connecting to Aang’s spirit and channeling Aang’s visions to Korra.
After Korra saw the flashbacks, she focused on Yakone’s bloodbending, but overlooked Aang’s removal of Yakone’s bending and the nature of the events leading up to it. Yakone had been defeated, defamed, and had no sensible path to take. His response? “Well, might as well bloodbend everyone in the room.” He subsequently vowed to escape and start a new life elsewhere, and immediately this plan was interrupted by having his bending taken away by Aang. Replace the courtroom with the council room, and Aang with Amon, and the situations are identical, even in pace. The visions may have been communicating that Amon’s key ability is the result of having obtained Aang’s spiritual side. Other characters such as Tenzin have remarked in shock that only the Avatar is capable of removing one’s bending, and that much could still be true.
To be fair, it wasn’t until after Korra’s visions that Amon removed Tarrlok’s bending skills. So perhaps upon reflection, Korra will make the connection.
To conclude, I currently imagine the finale to involve Korra and Amon in a one-on-one battle, trying to absorb each other, each one hoping to become the fully-realized Avatar. Korra wins and Amon crumples to a heap of cloak and copper on the ground.
Endnote:
I know a lot of people have read similar theories and retorted with the canonical restriction that only the Avatar is capable of multi-bending elements, and that breaking such a rule would be poor writing, and I’LL NEVER WATCH OR READ ANYTHING BRYKE PRODUCES AGAIN. Okay, I get that. But if this issue is inspected from within the story itself, there’s no universal rule or restriction that only one person can possess the power of all four elements, or that all four elements can only reside in one person. Rather, this was simply how things developed long ago in Avatarland, and as a result the four elements and their nations became balanced in an organic way. Things came to be, without rigid boundaries.
Even if there’s some form of cosmic authority over who can control how much, I personally regard that type of authority as an ideological concept—breaking a spiritual doctrine is not impossible, just unpreferable. Thus someone other than the Avatar being a multi-bender would be considered deviation from an ideology, not contradiction of logic or an unravelling of the series’ plot structure.
Also, because pictures make everything better, I’m just going to leave this here. 
