[quote=Hank]
The fundamental mechanics behind it are magic, because that's what it is.
[/quote]

"It's not magic; it's waterbending!"

[hider=*cough*]Sorry, couldn't resist. You're totally right and I agree with you on that.[/hider]

[quote=Sloth]
That sounds a little too complicated for someone to just pull off randomly. Ghazan had the benefit of (presumably) years of training, unless he was in prison for about half his life, but Bolin just sort of did it out of pure desperation. To me it just comes off as something it'd take years to even grasp the basics of, let alone use it in a combat situation. Then again Toph could do crap like turn sand into solid rock at the age of twelve so....screw it.
[/quote]

When asked how he did it, Bolin [i]did[/i] say that his life being on the line "kind of helped". 

I mean, the ways benders can use certain specialized types of bending (like a firebender using lightning or an earthbender bending sand, etc) strike me as sort of like skills that some people are just naturally gifted with. Theoretically, anyone can learn that skill, but some people just don't have that talent for it. Like, if you tried a certain sport and realized that you sucked at it, then you would probably (unless you had a really strong desire to become better at it) just say that you couldn't play X and just move on. That would be akin to, say, a firebender who decides he really can't bend lightening, and so they just say "I'm not a lightening bender". Meanwhile you have a friend who, despite lacking in experience just as much as you, picks up that same sport fairly quickly and realizes they sort of have a natural talent. That would be like a firebender who realizes that they [i]can[/i] bend lightening, so they go on to call themselves a "lighteningbender" and they continue to practice and get better at lighteningbending. 

Also, given how "natural talents" work in the real world, it makes sense that they can be somewhat hereditary, as well, though they don't have to be. For example, Toph basically invented metalbending, and then her daughters learned how to metalbend - and while it's sort of implied that they both inherited the skill from their mother, it's possible a lot of their talent just comes from being taught the skill, as well. For example, Lin presumably then taught the rest of the Republic City police force how to metalbend, though, going back to the natural talent thing, it would make sense to say that not every earthbender who tried out could really pick up on metalbending so easily.

Of course, that could just mean that being skilled in a certain type of bending just has to do with being skilled at bending a given element in general. For example, Azula was a lighteningbender, yes - which was a talent that Zuko didn't really have - but Azula was also just a lot more talented at firebending [i]in general[/i] compared to Zuko, so it makes sense that she'd be able to pick up on a more advanced form of firebending. But when there are multiple "advanced versions" of a specific type of bending (like lavabending and metalbending both being types of earthbending), it makes sense to say that a talented earthbender would have a much stronger leaning towards one type than another. For example, if you're naturally athletic, it would still make sense to say that you're inclined to be more talented in one sport than another. 

So, basically my interpretation is that Bolin had a natural talent for lavabending where he lacked one for metalbending. If that's the case, why did he not discover it until just then? Well firstly it probably has a lot to do with the fact that lavabending just doesn't seem to be as well-known across the Avatar-verse, and not a lot of earthbenders would've really considered it or been able to learn it from someone else. Think of it like sandbending from the original series. The sandbenders lived in the desert, so it made sense that such a skill would be common in their culture. But Toph couldn't sandbend at all, which, while probably partially due to the fact that she can't see through sand, was also probably due to the fact that she most likely isn't as familiar with sandbending - again, likely due to the fact that she seems to prefer to avoid sand in general. 

So given the fact that Bolin probably wasn't really exposed to lavabending prior to meeting the Red Lotus and really didn't consider it at all until that one moment - like Bolin said, his life was on the line, which is a strong motivator. I can see how adrenaline would boost a bender's abilities, perhaps sort of 'unlocking' that ability for Bolin by allowing him to realize that he had such a skill, and just didn't think to try it until he needed to save his own life (and those of his friends).

But yeah, while bending in general is kind of a "you have it or you don't" sort of deal, and benders can strictly only bend one of the main four elements (with the obvious exception of the avatar), I feel like the specific sub-sets of a type of bending are a skill that, theoretically, any bender of that main type can learn. I mean, I basically said that Zuko wasn't a lighteningbender, but the fact that he and Iroh could just [i]barely[/i] bend lightening by redirecting it through their bodies should say something.

[quote=Gowi]
That's a point I hadn't really thought about, I actually like this theory a lot. Though, as Sloth said that doesn't explain Bolin, but that's a whole other mess of "why". As far as Larfleeze's concept of genetics goes: I've always liked the idea, but I haven't seen much of it made sense of in the continuity. I mean that would've made Kya have an entirely unique style of waterbending if 1+1=2 but then again maybe it's not always a 100% hybrid bending gene or whatever?[/quote]

And this is why it hardly makes any sense to boil bending down to hard genetics. Like others said, bending is [i]spiritual[/i]. I mean, non-benders all over the world turned magically turned into airbenders thanks to spirit nonsense, and no common ancestry or anything was ever really implied between the chosen non-benders. 

I think it makes sense for talent regarding a bending sub-type to be at least somewhat hereditary, if you subscribe to the whole natural talent idea, but not only has the canon in both series made it clear that the origins of the four main bending types are spiritual, it’s also been made fairly clear that gray areas don’t really exist between the four types, and there really never has been a canon “hybrid” bender, again with the obvious exception of the avatar, but even then, the avatar’s bending also exists for spiritual reasons, so… yeah.

[quote]I don't know, it's a mess.I still don't like waterarms or combustion girl in any form.
[/quote]

To be honest, I really only like Combustion Girl because she’s a callback to Combustion Man from the original series, and his bending was a really unique and interesting concept. 

As for “waterarms”, a thought occurred to me while spending countless paragraphs overanalyzing the series: ever heard of phantom-limb syndrome? When amputees still sort of “feel” a certain limb even though they don’t have it anymore? They’ve discovered that this is because the parts of your brain that control lost limbs still exist even if the limb itself is gone, and they’ve used this discovery to invent high-tech prostheses that connect to an amputees brain and allow them to control the fake limb the same way they would control a real one. It’s possible that waterarms (whose real name I honestly don’t remember, either) has learned to use waterbending in a similar way. Her arms don’t exist anymore, but the part of her brain that controls her arms still does, so maybe her bending ability allows her to use water as a substitute for her arms, controlled the same way that real people control those high-tech prostheses.