There seemed to be a large dislike with the new abilities introduced to bloodbending and energybending after "Out of the Past" and the season finale. Why? Did we really know all we could about these abilities? Were they ever thoroughly explored and utilized so we might know all of how they worked? I've decided to try to understand and to explain the new abilities introduced to these bending arts.
Unlike other subskills, bloodbending was never used more than twice in Avatar: The Last Airbender. It was briefly summarized but never completely explored. All that was needed to know was that the technique was to control another human being like a puppet; perhaps this is where the controversy lies. In order to control someone like a puppet, the puppetmaster must move their hands. I won't argue with that as I can understand why one would feel that is necessary to bloodbending.
I will counter the movement argument with Combustion Man (a.k.a. Sparky Sparky Boom Man). While I understand that much movement isn't exactly important for firebending (e.g. breathing fire), I feel this can be applied to bloodbending. The idea behind Combustion Man's unique talent was that he had an overdeveloped third eye; so anything he could see, he could blow up. I take that to mean that his chi (which is linked to bending, of course) was highly focused/overdeveloped which allowed him to create a single, laser-like fireblast.
Yakone, Noatak/Amon, and Tarrlok (I'm sure he had it though he never honed it) all possessed a similar, uncanny ability. I imagine that their chi was also overdeveloped which allowed them to control whomever they could see. Because one can see multiple people at a time, this explains why they could control more than two people at a time (correct me if I'm wrong, but even highly skilled puppeteers can control more than two puppets at once).
Yakone was labelled as dangerous, and what's more dangerous than a bloodbender that can control people with his mind? At least with Combustion Man, Team Avatar could dodge his attacks (or throw boomerangs at his face).
As a side note, I have to say how crappy it must have been for Sokka and Aang to be bloodbent...again.
How Amon was able to use it to remove bending, however, was a tad more confusing. Explore the subskill of healing and suddenly, his power begins to make sense. Healing follows the chi paths therefore bloodbending must also follow these paths. While the former restores, the latter can destroy. Unfortunately, because bloodbending can sever the chi paths, it prevents healing from ever repairing the damage it causes. I suppose it's because healing cannot "retie" those cut paths. It's as if the chi would have to be "tied" or "glued" back together which is beyond healing's capacity.
This also makes me think that healers have the potential to be great bloodbenders.
|"The true mind can weather all the lies and illusions without being lost. The true heart can tough the poison of hatred without being harmed. Since beginning-less time, darkness thrives in the void but always yields to purifying light. In the era before the Avatar, we bent not the elements, but the energy within ourselves. To bend another's energy, your own spirit must be unbendable or you will be corrupted and destroyed."|
|— The lion turtle|
Like bloodbending, energybending was only seen twice in the original series, and its summary was somewhat cryptic. Soon enough, we saw the effects of the powerful technique. By Avatar's end, energybending was the method of removing bending. But by Korra's seasonal end, it also became a method of restoring bending. Is energybending any better understood? Not really.
All we know is that energybending is the only and truly permanent method of removing (without being a psychopath) or restoring bending. It must also manipulate the chi paths but in such a way that one is not corrupted (if successful). This leads me to believe that waterbenders are much more closely linked to energybending than the other elemental benders. Perhaps I'm just reading too much into it, though. But waterbenders also learned to bend their element by watching the moon push and pull the tides while the other elemental benders learned from badgermoles, dragons, and sky bison. Maybe the first elemental bender was a waterbender. Maybe the first avatar was a waterbender.
As for how Korra was able to energybend without being corrupted or destroyed: Avatar State.
What I want to know is what was the significance of energybending before the era of the avatar? Since nobody was bending the elements yet, it couldn't remove or restore that bending; so what exactly did energybending do?
Because its past is such a mystery, I can accept that energybending can take and restore elemental bending. If it can take away bending, it's only logical that it can also give back bending. I would also like to know if energybending can go so far as to give bending to a person that never had the ability to do so. I doubt it, but it's not as if the art has been detailed with concrete rules that would ever prevent that from happening.