The first time Katara brought someone back to life, she had spirit water on her side and the favour of destiny to urge her along; she thought it was a miracle then, a one time thing, not something she could repeat even if she wanted to.

But then she did it a second time: with the magic of blood she had so feared to learn and the power of the moon in the sky, desperately reaching out to force a heart to start pumping once more- and life bloomed back into the body before her.

Katara did not mean to continue, she did not want to, but as her bending prowess grew – fighting and building and healing, and also, despite her will; her control over blood – so did this, and before she knew it took merely a twist, a pull, and she could bring all but the most damaged back to life: and how could she choose not to?