[Part One]

There has always been an Avatar in Republic City.

The government is corrupt, the police are spineless, and there are villains swarming around every dark corner of the city – not just your run of the mill Triad bosses who care about money and a bit of petty power, but honest to god supervillains with masked faces and fresh blood under their fingernails and a taste for death. Every day people die, and every day their murderers go unpunished. In Republic City, that's way it is: if you haven't got power, you haven't got a hope.

With no one to protect them and everything to be afraid of, it's no wonder that the people of Republic City have taken the law into their own hands. Every district has its own neighbourhood watch, anonymous watchmen and women with hooded faces, sharp eyes and even sharper knives, who watch out for their own and don't tell tales.

Among those men and women, there are always one or two with a special gift: the ability to breathe fire, or the strength to tear rock straight out of the earth just by sheer force of will. And sometimes those special few take defending their city just that little bit further. They put on masks, they take on new identities. They go out into the open and fight.

You can't have villains without heroes, after all.

Any child could tell you about the most famous heroes of all, the long gone greats like the Painted Lady, who defeated the Puppetmaster by using her own powers against her, or the Blue Spirit who faced the Phoenix King and lived. They all wore masks, of course. Heroes need masks, if they want any hope of having a normal life.

Only the Avatar fights without a mask. Only the Avatar gives up everything – freedom, anonymity, any hope of surviving to a ripe old age – in order to protect Republic City from its enemies. The Avatar can be old or young, male or female, but the Avatar is always unmasked, always brave, and always a symbol of hope.

The Avatar always dies. The Avatar always comes back again.

The last Avatar passed away twenty years ago. Lin knows. She was there. She remembers her mother's face, twisted up with grief and fury and – most terrifyingly of all – a bone deep kind of weariness, the kind that doesn't fade away after a good rest. She remembers her mother pulling off her domino mask and her bandana, letting her identity as a hero fall forgotten to the floor.

I'm done, kid, she said. I can't do this without Twinkletoes. It's gotta be you now.

And Lin, who'd had a good thirty years of freedom, of living safely in her mother's long shadow, lifted her mother's mask off of the floor and said, I guess I'll need to pick a name.

She knew her duty.

The night is dark and quiet, and the sound of metal on metal as Lin uses her cables to leap between buildings cuts through it like a knife through butter. She feels the wind against her visor, the glittering city whistling beneath her feet, and tries not to think of Avatar Aang, who died too young and had a smile like sunshine. She tries to put the rumours that have been swirling around the city – the Avatar's back, the Avatar's back - to the back of her mind. Aang had wanted to be the last. He would be the last.

Lin leaps from the roof to the ground, metal cables leaping down after her. She sets her feet steady on the ground and straightens, sold and strong. The boy in front of her – the boy who was waiting in the dark alley, nervously twisting his hands in his pockets – gives a yelp and stumbles back.

"Oh man, what do you – it's you," he says, recognition and relief dawning. "Chief. I didn't think you were coming. I – I didn't know if you got my message."

Lin stares at him through her metal visor. The boy shifts, trying to hide his unease. She knows how she looks, metal glinting on her face, only a hint of her mouth and her eyes bared and impassive. She looks like something to be afraid of. Wise boy.

"Well?" she says, voice clipped. "You wanted to talk to me. So talk."

He stares at her, a hint of fire in his eyes. This one has a temper; a bit too much bite for his own good. His voice is tight when he speaks again; trembling and fierce, caught between fear and anger.

"Everyone's going to know soon, but I saw her save some friends of mine and I thought – one of the good guys should know first." He takes a deep breath. "Chief. It's not a rumour this time. It's all true. The Avatar's back."

Lin feels her insides go cold. Oh. Oh no.

"You're sure?" she asks.

"I saw her face," he says.

"Well then," she says, because there's nothing she can say. "Thank you."

The boy nods. Jaw tight. Lin sends a cable flying, latching it to a rooftop, readying herself for the leap.

"Oh, and – Mako?" she says. "A word of advice: get yourself a mask and a new name. You're going to need them."

"I don't want to be a hero," he protests. But Lin is already in the air, moving as fast an arrow, and she doesn't have the time or the inclination to respond.

xxxxxxxx

Avatar Korra, they call her.

Just a girl, they call her. Still a teenager, really. But Avatar Aang had only been a child when he'd first appeared, all bright eyed and quick and cheerful, and he'd survived somehow…

But Avatar Aang had friends, of course. A team. The Painted Lady and the Blind Bandit, and a watchman and watchwoman who travelled hooded and nameless, as all of the watch did, carrying a sword and a fan between them. This Avatar Korra is by all accounts alone. They say she came from outside the city, from a distant outpost on the South Pole. She doesn't know the city. She knows nothing. She's brash and hard as nails and alone, alone, alone.

Lin hears it all and hates this girl, hates this Korra, for throwing her life away.

She will die. She will fight for Republic City, burn and kill and beg for it, but one day the fighting will kill her, because that is what happens to the Avatar, that is what always happens to the Avatar. And if she has no one to help her; if she's really alone…

Lin has to find her.

xxxxxxxxxxx

In the end the Avatar comes to her.

There's a new villain in town called Amon, with a hollow-eyed mask and an army of chi-blockers at his beck and call. Lin has two of his chi-blockers cornered, bound up with metal cables against a wall. But there are more coming, and Lin can feel their movement reverberating through the earth beneath her feet. Closer, closer. Her heart pounds; she can feel adrenaline roaring in her ears. As one jumps down from the roof above her, she slams them hard against the wall with others. One hard lash of a cable is enough.

"Need some help?" asks a voice. A girl's voice; terribly young, but warm and melodic. "There are more coming around the corner. A lot more. Just so you know."

"I can handle this," snaps Lin. Just what she needs, a rookie hero getting under her feet. Fantastic. "So why don't you –"

She turns, and the words die in her throat.

The woman isn't wearing a mask. It jolts Lin hard, seeing a bare face on a hero. The girl's face is dark and unlined, with wide clear eyes and a generous mouth that widens into a tentative grin as she takes in Lin's metal visor, her metal suit. She's a lovely thing, Lin thinks inexplicably. (Oh what a waste, what a waste.)

"You're the Chief!" she says. "The Blind Bandit's daughter – right? I've heard so much about you."

"So you're the fool Avatar," Lin says in a hard voice. "I've heard about you too." She calls a cable to snake around her wrist, as sleek as a whip against her palm. "You should leave."

"But you're going to need my help with those chi-blockers," protests the Avatar, her wide eyes narrowing as she takes in Lin's hard stance, her harder words. Good. She shouldn't trust Lin. She shouldn't trust anyone in this godforsaken city.

"I mean leave the city, Avatar," says Lin. There's an ugly pain in her heart as she looks at the girl, speaks to her. "Get out of here while you still can."

The Avatar stares at her head. Shakes her head.

"I'm not going anywhere," she says, stubborn. "The city needs its avatar."

"The city has enough heroes," says Lin, because it's the truth.

There's a motorcycle roar as the chi-blockers come around the corner, two riding and three on foot. Lin snaps her gaze away from the Avatar, focusing all her attention on their mutual enemy. She snaps the cable outward – sends one chi-blocker flying off of their motorcycle, straight into the one on the ground, and allows herself one brief moment of satisfaction before turning her attention to the remaining enemies.

There's snap and a sizzle. An arc of flame leaps through the air, and the second motorcycle plus chi-blocker skids across the ground and slams hard into the building opposite. Avatar Korra lowers her hand, light embers still dying on her fingertips. Then, quick as a prey animal, she darts forward, dragging the earth up with a sweep of her hands. The last two chi-blockers are trapped almost instantly, bound tight in coils of rock. The Avatar grinds to a halt, one hand still outstretched.

"Do you think I can't handle myself?" the girl demands. "Because I can."

She curls up her hand. The bindings get just that little bit tighter.

Lin takes a step towards her. Two, three. She grabs the girl's hand, metal on soft flesh, and uncurls her fingers. One by one. Careful, she thinks. Careful.

"Go home, Avatar," she says mildly – as mildly as she can. "Go home and live a good life. Go home to your parents. This city will eat you whole." She holds the girl's hand, just a second too long, then one more, then anothers; wonders if the girl will be able to smell the ghost of metal on it later, so very like salt and blood. "Go home," she repeats.

The girl pulls her hand back.

"I am home," she says. "I'm not a child. I know what I'm doing."

Lin laughs. She can't help herself.

It's not a happy sound.

"Of course you do," she says.

The Avatar has a hard, stubborn set to her jaw that only gets worse when Lin laughs. She pointedly takes a step away, then turns sharply on her heel. Shoulders hunched. Hands carefully held flat and open.

"It was good to finally meet you, Chief," the Avatar says stiffly – a blatant lie. "I guess I'll be seeing you."

"This is my district," Lin says. "If you come back here, you will."

The Avatar gives her a look – one flash of fierce, mistrustful blue eyes – and then she's off, running on swift feet, dark hair streaming behind her.

Lin hopes she never sees her again.