Bending of water and air inside people's bodies

Question

I never got around to watching Avatar when I was younger, so now I am finally catching up by watching it with my kids, which makes it even better :)

Anyway, there is one thing I have been wondering about: when Aang and Katara (or any other water bender) are fighting against someone why don't they just bend the air and water inside their opponents' bodies. I mean, our bodies are 65% water so it should be quite easy. Also, Aang could manipulate the air in their lungs or something similar which could easily disable (or even kill) them.

PS: We have only watched 2 seasons so far, so if it is explained later please bear with me. Also, I am familiar with blood-bending, but I am not talking about controlling people - more like using the water in their bodies to lift them or hurl them away (since killing is not really this show's style).

Answer 1

Bloodbending is used to lift and throw people in the shows, most notably Legend of Korra - Book 1, by

Amon

Also, in the episode where bloodbending is introduced, it's made clear that bending water in living things is a novel concept invented by Hama, that Katara hasn't seen or considered before. Supposedly it's not as easy or obvious as just bending regular, free water.

There are other examples on the show of novel uses of bending "non-pure" versions of the elements, that require either special training or a rare insight. Toph was the first person to invent metalbending, by bending earth impurities inside refined metal. The swamp benders bend the water in vines to create monstrous disguises.

Answer 2

This is less of an issue of can they, and more of an issue of "would they?"

The most highly skilled waterbenders are able to blood bend. We see this with Hama, and Katara in The Last Airbender and Amon in Korra. We also see some water benders bending water in trees and plants.

But Katara has a major philosophical issue with it as controlling someone, even an enemy, goes against everything she believes in. She only does it in the most dire of circumstances.

Katara is a waterbender. While waterbending is often used for attack and defense, their true talents are in healing. That said, the evil waterbenders we see, do use it for purposes you describe, using it to hold/stop or throw their opponents.

Aang, while never demonstrating either ability that I can recall, would have similar issues. Remember that Aang was raised as an Air Nomad. It can be noted that Aang was not necessarily a particularly skilled Airbender, having not finished his all of his training. Air Nomads are non-violent, and early on, Aang has a lot of difficulty intentionally harming someone. Airbending is meant to be used to evade fights, not participate in them. The destructive nature of firebending, and using bending for attack comes into play in a big way when Aang must learn to firebend, as Aang refuses to firebend ever again, after accidentally hurting someone. Similarly, Aang has psychological difficulty with Earthbending, as it is the psychological and elemental opposite of Airbending.

Using bending for such attacks just isn't in the nature of most benders, and especially not for the ones we follow.

Answer 3

Why Aang and Katara don't use their bending on their enemies' fluids to cast them away?

You mentioned that Aang and Katara are pacifist so they wouldn't use that ability to kill people by bending the water and the air inside them to make them explode or something like that, which is correct. However they could use it to send them away, right?

I believe the reason they don't do so is because it's overly complicated for such a simple task. Why bend people's lung's air if you can simply bend the air around them to hurl them away? It serves the same purpose and it's easier since it's "grasping" and bending the air you can see as opposed to the one within the flesh.

As for Katara, she almost always had water at her disposal and didn't need to use people's fluids.

In season 3:

She once use her own perspiration to escape a prison as she doesn't have water but it's a pain at the moment. It would have been easier if she had waterbended her fluids then, but if she didn't think about it, it's probably because it's not pure enough (bloodbend) so she simply couldn't.

And later

She learns to bloodbend but she only uses it when she has to, because she doesn't have water to bend or to counter her opponent bloodbending.

Then why didn't their opponents use it since they didn't care about killing?

In The Season 3 of Legend of Korra, there's one occurrence of an airbender who airbends Korra's lungs' air to suffocate her. But once again, it's a very powerful bender who does it. So if people don't usually do it it's simply because it's difficult: it demands more power, precision and time. It's easier to simply hurl them away and knock them out against a wall, for example, than to bend the air out of them. Plus you can attack multiple people at once this way.

As for water, once again, since you can't waterbend fluids but only bloodbend (which is thus more difficult) there's only a small number of people who could bloodbend, and for almost all of them it was only during the full moon. So it's also simpler to use the old-style waterbending to fight.

So their opponents simply weren't strong enough to do so and wouldn't have much reason to do it anyway.

TL;DR Why bother to bend enemies' bodies if you can bend the pure water/air (which is simpler) to cast them away or knock them out?