Katara: It’s not magic. It’s waterbending, and it’s-
Sokka: Yeah, yeah, an ancient art unique to our culture, blah blah blah. Look, I’m just saying that if I had weird powers, I’d keep my weirdness to myself.
So I wanted to talk a little about Katara, because I think we often focus on her grief for her mother, and forget her relationship to her culture, and her experience of the Southern Water Tribe genocide (unlike the Air Nomads genocide, which was for the greater part over after four big terrifyingly effective simultaneous strikes, this one took place over a long length of time - more than 40 years? 50? - and it wasn’t total, but it definitely was one. genocide = the deliberate and systematic extermination of a national, racial, political, or cultural group, fwiw)
(Kanna’s village - before and after)
All of the Southern water benders were exterminated or taken away to rot in prison (where they all died eventually except for Hama). Katara was born the only bender left in the whole South Pole. Then when she was eight years old, she survived a raid that was meant to kill her, but took her mother instead (she probably was too young to realize that, to her it must have been a question mark up until she met Yon Rha - gratuitous cruelty? Why her mother in particular? They took nothing else!).
So Katara from a young age had a double burden to bear: that of her mother, and the legacy of her bending (and she was shown as painfully aware of her situation and what it meant on both front). But here’s the thing: Katara could be a mother, she was naturally good at it, and her grandmother could teach her what she didn’t already knew. Her family and tribe demanded that of her, they needed her to be that for them (especially after her father and the rest of the men basically abandoned them). However, there was no one left to teach her how to waterbend - she had almost no hope of ever becoming a master without formal training, her brother thought it was silly and weird and let her know, her grandmother thought it was a waste of time. But she kept practicing, because she knew how important it was, to her and to her tribe, that she kept trying (as the only one left who could).
(…an ancient art unique to our culture, blah blah blah…)
(Of course she would obsess over that waterbending scroll)
When she gets to the North Pole, she meets Pakku, and with him the opportunity of finally becoming a true master. But because she is a girl, he judges her unworthy. He judges her, the only remaining southern waterbender, unworthy of carrying on their culture. The Fire Nation didn’t care about the gender of their prisoners, men and women - they all fought side by side for their freedom in the South, and they were all taken away to the last one, and killed to the last one. In the South, the women had the choice to learn how to fight, or be defenseless. And privileged master Pakku couldn’t possible realize the extend of what he was denying her in that moment.
Katara had to prove herself, she had to earn her right to these teachings. And if she had been less good or less stubborn or not Kanna’s granddaughter - well the North would have refused their sister-tribe the power to use their common cultural heritage to fight back against the nation that destroyed them.
(It’s sexist and terrible.)
Meh, thankfully, she was that good, stubborn, and Kanna’s granddaughter, and she did get to become a master.
But, of course, her story doesn’t end here, and wrt her culture, the next chapter is a much more traumatizing experience. In the Fire Nation, she meets another master. This time it’s an old woman from the South like her (“You’re a waterbender! I’ve never met another waterbender from our tribe!”), and she is, ah, more than willing to help her.
Look how happy Katara looks at the idea to learn from her in particular:
Katara: I can’t tell you what it means to meet you. It’s an honor! You’re a hero.
Hama: I never thought I’d meet another southern waterbender. I‘d like to teach you what I know so that you can carry on the southern tradition when I’m gone.
Katara: Yes! Yes, of course! To learn about my heritage… it would mean everything to me.
But when Hama starts her lesson, the techniques she teaches have been obviously developed with one goal in mind: survival in enemy territory. They can’t possibly have been invented in the South Pole, where water is abundant everywhere. They are deadly and cruel, and the damage they do to the environment leaves Katara sad and uncomfortable, but Hama waves that off as unimportant. It doesn’t matter, she doesn’t have the time to worry about flowers or beauty or nature. To her that peace and beauty is probably just an illusion anyway, a lie: years after her escape she is still living the war, and war is ugly and rotten and messy (her world is ugly and rotten and messy - this is her comfort zone).
The last technique she teaches Katara is bloodbending. She forces Katara to learn something she finds disgusting, repulsive (just like Hama was forced to learn?) by torturing her (Hama was tortured), by overpowering her, invading her, making her lose control over her own body, bending her blood (Hama herself is clinging to the last remain of control she managed to get back after rotting in prison for years), and finally by threatening to have the two people she cares most about in the world kill each other right under her eyes (Hama lost everyone too, she had to say goodbye).
(Katara: But, to reach inside someone and control them? I don’t know if I want that kind of power.
Hama: The choice is not yours. The power exists…and it’s your duty to use the gifts you’ve been given to win this war. Katara, they tried to wipe us out, our entire culture… your mother!
Katara: I know.
Hama: Then you should understand what I’m talking about. We’re the last Waterbenders of the Southern Tribe. We have to fight these people whenever we can. Wherever they are, with any means necessary!
Katara: It’s you. You’re the one who’s making people disappear during the full moons.
Hama: They threw me in prison to rot, along with my brothers and sisters. They deserve the same. You must carry on my work.)
And this, this, is the only truly southern waterbending Katara is ever going to learn. This is her tribe’s bending heritage, what’s left of it: blood, grief, suffering, hatred, loss of control over both your body and mind (because it’s terrible, but I think that’s what’s implied by the show: bloodbending makes you lose your mind. Hama’s only mean of regaining physical freedom ended up trapping her in another nightmare). Hama gifts her with a power she despises (but will use anyway in her darkest hour when she loses control) and a philosophy of violence and revenge.
Katara chose peace and forgiveness. As an adult, she will have bloodbending outlawed, she will become the greatest healer in the world, and she’ll teach her daughter, the next avatar, probably many others. These choices matter, and we should talk about them with that background in mind. Katara redefined her heritage - or rather she created a new one for herself: she refused the condition that was forced upon her (bloodbender) and ensured nobody could legally do to someone else what Hama did to her (and it’s implied this law is valid anywhere in the world). She transmitted Pakku’s warrior teachings, the ones she fought for, to the next generations (and did a great job of it!), but she also taught them how to heal, refusing to separate the arts as in Northern Water Tribe tradition - and healing was something she discovered by herself, that she felt was always a part of her. At that, she became the universally acknowledged best. Her legacy, despite everything that happened to her, will never be one of violence.
tl;dr: Katara is one of the strongest fictional characters ever created bye