The boy shoots her in the chest.
He doesn't, not really, but she can feel her heart break into two as he faces her across the room. His sister is at the side, and she's taunting him. Katara knows she is.
She wonders why she thought trust, and faith, and her heart . . . why that was enough. She wonders why she thought she could ever be enough.
"Don't do this, Zuko," she backs up to the wall - the door is a bit to the left and she can escape if she just . . . manages to keep him from pulling the trigger for a few moments. His eyes spark, and she knows that goodness she'd seen in him for the past few months . . . she knows that's still in there. Somewhere. The gun in his hand is shaking, which is strange. His hands are shivering. Zuko always runs warm.
Zuko makes dumb decisions— she knows he does. He's committed arson without thinking twice, has set off bombs with her and run away, but despite his usual failures to think things through he's almost always at least . . . confident in what he's doing. He doesn't look sure of himself. Azula crosses her hands and stares at him as she stalks over to Aang, who's sprawled across a bunch of wooden crates in the back of the warehouse. Katara knows he'll get up soon. He always does.
"You want father to trust you," Azula snarks at him. "You made the right choice, Zuzu. He'll be proud of you when we kill the Avatar," she jerks her head towards Aang. "Now just kill this one. She's boring. Not even putting up a good fight."
"Don't do this," Katara repeats, shifting every so slightly to the left when Azula tilts her head away for a second. Zuko notices the movement and seems wary, but keeps the gun trained on her. Katara lifts her chin up and gathers all her courage and breathes out. "Please, I thought you changed. I thought we—"
"What?" Azula is back, and she almost looks as though she's going to stalk over to Katara before she decides that's a waste of time. "We? Oh, don't be dramatic, you peasant. Kill her, Zuzu," she snarks, and Zuko suddenly looks terrified. "Now!" Azula insists.
And then the ceiling falls down. Aang is up again, facing Azula, and something is whirring up against the building's ceiling. Katara spends half a moment looking up— there's a excavator pulling the building apart. She can only imagine who's inside it; likely Toph and Sokka. And that means that it's time for her to leave. She needs to leave.
She tries one more time, but this time she asks a question. "Why?" Before he can respond, she finds tears clouding her eyes in a way that she really doesn't want them to, and all she can think about is the past month, and the way Zuko walks her home at night and lets her touch the scars his family gave him, the way he kisses her on the cheek and tells her it'll all be alright, that they have so much in common.
His grip on the gun is tighter now, and he looks more sure of himself. "I have to— I have to," he pleads with her, his rough voice shaking, and there are tears in his eyes too, falling down his scar, making a path through the dust and the dirt that's covering them. "It's all I've ever wanted."
"Is it?" Katara asks. She needs to turn away. She needs to turn away, but she can't. His eyes are shining, and she holds out hope that isn't just because of the sun. "I thought . . ."
At that his eyes harden.
Katara turns to the side and kicks open the door and runs for her life. She hears the distinct click of the gun behind her and then hears him shoot it and thinks it is the end. In those moments she thinks about her family in the south and the hands which had held her last night.
Nothing happens. Something falls to the ground. Katara flips around and sees Zuko on his knees. His gun has been empty. She knows that now. She stops.
He's looking at her as though the world is ending. Someone grabs her— likely Sokka, maybe Aang, if he's gotten away from Azula— and she lets them pull her away. She looks him in the eye and tells him the truth. It has.