Disclaimer: I don't own AtLA or LoK.
She was an empathetic person, very much like her mother.
And she tried to remind herself of this as her limbs jerked and her bones creaked, her body gripped by an invisible force. She tried her hardest to push back against it, and her veins would stop lurching occasionally in response- but the three criminals in front of her always regained their grips.
The man in the middle was hesitant, she could tell, but he shook his wrists and positioned them into the start of a motion she knew all too well.
He was going to snap her neck.
There was no way to repel all three of them at once. But she was stronger than all three of them combined, and she could clutch at them and shove them around until they were knocked out. She could run. Only one thought kept her from doing just that:
"Other than Hama… I had bloodbended someone once. Out of pain and fury. I regret losing control over my sense of self. I regret it, even if he had been the man who killed my mother. I would never take away someone's will over themself, never again…" Katara's voice rang in her ear, clearly. Her mother had told her this story not long ago. "You have to remember who you are."
But this wasn't about revenge. This was about self-defense. And she could feel her neck jolting around spasmodically, about to give way any second.
So for the second time in her life, she reached out and caught hold of someone's veins.
She had the benefit of study and practice on specimens to make up for her lack of experience on people. It wasn't hard for her to grip their muscles and push them back against the alley wall. They gave outbursts of pain and fell, only to be lifted back up by her will. She dropped back to the ground and firmly landed on her feet, feeling a new wave of power washing over her in a baptism of realization: she could easily kill them. She could very well exploit her strength and grab hold of each of their internal fluids and strike at each of them until they were lifeless crumpled puppets at her feet. And suddenly, the temptation to take their lives was so potent: she could only imagine Lin's screams, Bumi's cries of anguish. She could only imagine the burning they felt as their blood rushed backwards, battering them internally- each move forced upon them a fresh violating stab.
The thought of killing them was so irresistible, especially when the one in the middle- the hesitant one- broke free of her hold and tried to control her again. And as she struck anew, she was sure that they would not leave there alive. She reached out to the ones on the left and right, summoning all her will, and constricted them even more.
She was struck by yet another voice- her father's, ringing loud and clear. She had been seven years old, on a trip to Ember Island, playing in the sand when a beetle had decided to come and jab her with its pincers. Indignant, she lifted her sandal, but a hand on her shoulder stopped her. She turned her head and caught grey eyes that mirrored her own. She had reconciled whatever she beef she had with the bug by these few words, "All life is sacred, Kya."
But these lowlifes had done more than bite her, and the thought of Lin's eyes widening to an unfathomable girth before shutting tightly, while Bumi keeled over as his heart stopped had washed away the image of those wise grey eyes.
She did whatever came instinctually, and rolled her wrists before curling her fingers. Two necks popped simultaneously, and they fell like marionettes. She fixed her gaze, murder in her narrowed eyes, as she caught hold of the man who was left. He was young, maybe her age- but this did nothing to deter her as she tightened her hands into claws and pushed everything up into his head. His arms flew up to the sides of his skull as a twisted scream was ripped from his throat, the pressure too much to bear. A twisted grin formed on Kya's lips as his skull cracked, and blood splattered on the wall behind him, before he too feel face first into the dirt.
As she ran from the scene, she looked at the blood staining her palms and remembered her empathy. And that's what made her collapse.