Set between Seasons 3 and 4.
Baby steps.
At night, she dreams of running, Naga at her side, her boots slapping the tundra. She dreams of Zaheer leering over her, of standing on her own two feet and pushing back when he pushes her. But she wakes, always in a cold sweat, always too weak to stand.
Katara tries to understand, Korra can see it in her face. But she doesn't know what it's like to be trapped in her body, in her mind.
When she can't force her feet to take another step, when she collapses at Katara's feet, Korra's mind drifts to those blank olive eyes following her every move. She knows he's locked away, but he's locked in her head and Korra's paralyzed with fear.
A fine Avatar she is. Sometimes she tries to write to Bolin, to Mako and Asami and Tenzin. But the words never come— it's like the air's being squeezed out of her head and all she can think about is catching a breath— and her friends' letters slow from a flood to a trickle.
They don't need you, her mind chants (shut up, you know it's true). They don't miss you much anymore (they're my friends, they've forgotten all about you).
Zaheer has poisoned her mind as well as her body, leaving Korra questioning the structure of things, her place in the world, like she never has before.
Baby steps. That's what Katara says. Korra makes it to the other side of the hut, then back again. Progress. She picks up a pen, writing back to Asami after months of silence. Nothing personal. Just news about her tribe and the stories about Aang that Katara's told her. Questions, too— how's Tenzin's family (do they miss me?), what's your company up to (how are you doing?), how is Mako doing (are you dating him?).
At night, Korra still dreams of running through the tundra, but when she wakes in the morning, slowly, surely, she can stand.