No action is more taboo in Avatar: The Last Airbender than bloodbending, which occurs when a very skilled waterbender can manipulate the blood flowing within a living being. This allows them to control the other person's movements or completely immobilize them.
In fact, Katara bans its use as a political figure in the emerging Republic City before the events of Legend of Korra. Why is she so afraid of it, and how did she learn to use it in the first place? Here's a refresher on where, when and why the level-headed Katara brushes with such a dangerous skill in Avatar: The Last Airbender.
How Did Katara Learn Bloodbending?
Katara learns how to bloodbend from Hama, a Southern Water Tribe waterbender who was captured by the Fire Nation. She appears as Team Avatar surrounds a campfire, telling ghost stories. Hama invites them to her inn for a cup of tea, and after snooping around when she leaves, Team Avatar realizes she is from the Southern Water Tribe -- just like Katara and Sokka.
After Katara reveals that she, too, is a waterbender from the Southern Water Tribe, Hama offers to teach Katara all she knows. As they train, Hama reveals she used bloodbending to manipulate a Fire Nation guard to open her cage when she was captured. When Katara voices her moral doubts about learning the technique, Hama's mood takes a drastic shift. She demands that Katara avenge her mother's death by any means necessary.
Katara realizes Hama is responsible for the disappearance of innocent Fire Nation people and rebels against her. She overcomes Hama's control over her body, but is forced to use bloodbending herself when Aang is almost killed by Sokka under Hama's control. As Hama is being taken away, she sarcastically congratulates Katara on becoming a bloodbender.
When Does Katara Bloodbend?
The events above occur in Book 3, Episode 8 of The Last Airbender, titled "The Puppetmaster." Katara also uses bloodbending one more time in Book 3, Episode 16, "The Southern Raiders" after mistaking the Southern Raider captain as her mother's killer. After agreeing to help Katara find the assassin, Zuko leads her to the Southern Raiders' ship. They eventually reach the ship's captain and, in a blind rage, Katara subdues and forces him to look her in the face. After a brief moment, she realizes he isn't her mother's killer and walks away.
Can Katara Bloodbend Without a Full Moon?
Being able to bloodbend without a full moon may be achieved after training the taboo skill. Katara refused to use it in The Last Airbender due to her moral obligation, so she never got the chance to train it. In fact, the two times she uses it are during a full moon, so it is assumed she cannot bloodbend outside of this situation since she didn't use it during her pivotal final battle with Azula. With this in mind, Legend of Korra's Yakone and his sons Noatak and Tarrlok could bloodbend without the use of the full moon -- because they trained the power in secret.
Can Katara Resist Bloodbending?
Katara can definitely resist bloodbending, as she is seen fighting off Hama's control even before learning the technique herself. There is much debate about whether bloodbending resistance is achieved through being a better waterbender than the other person or merely being a powerful bender overall. Katara is definitely both, yet the same is seen when Aang resists Yakone's bloodbending in The Legend of Korra as he goes into the Avatar State, and when Mako frees his hand in order to strike lightning at Amon.
Morally, bloodbending is wrong. If Katara had taken time to develop the skill, she would have gone mad with power and The Last Airbender would have taken a much darker turn. Luckily, she stood her moral ground and remains the powerfully good-hearted waterbender that Avatar fans know and love today.
