This is an idea I came across while writing my Valar Morghulis series. It is vaguely based on the same idea (second chance, rebirth), but switches stuff around and brings Cersei to Middle Earth.
It also includes a lot more crack than the other one, but I hope you enjoy badass Elven Cersei.

Disclaimer: I don't own anything

Cersei

It's green fire, in the end, green fire and tumbling rocks and pain, and yes, maybe not only a little bit of regret. Maybe it's a hella lot of it, but people tend to regret things once the roof is raining down on them, she supposes. She can die with Jaime, true, but that has a lot less shine now that it is actually happening. Her thoughts flicker to her children, her perfect golden babies: Sweet Tommen, who had to grow up far too quickly, and her beautiful Myrcella who was far smarter than she ever realized. In the end, she made the same mistakes her father did, prioritised the heir and neglected the younger boy and the girl and the world wasn't better for it - on the opposite. Cersei is proud, but even she isn't that blind, she can see Joffrey had become a monster. She knows what he did to the Stark girl, the humiliation and pain. Forcing her to look up at her dead father. She shudders, and it doesn't only have to do with the dust and the roaring around her. Jaime and her, they had created a menace, and she can't even fault whoever it was - probably Lady Tyrell - for not letting the same happen to her precious Margaery.

Sure, she will always love her first-born son, but -. But Ned Stark's face floats into her mind unbidden, cold eyes, unpleasant, only dark and deep as he surrenders to take the black. The short look of shock as Joffrey calls for his head. Then it's all over. No, Cersei detested that man, this idea of honour, just laughable. And yet. His children live, at least partly, while all of hers are dead. So maybe he did something right, that prick. Why she wastes her last precious seconds thinking about him she doesn't know though, so she turns back towards Jaime next to her. She holds on to him as long as she can, until her lungs give out, and she feels nothing anymore.

~ o ~

When she wakes up, there is a grey mist around her, a fog of some sorts, and certainly no Jaime. There is no pain, though there should be, and she looks around and down - well, damn it, because apparently, she doesn't exist anymore. But she can feel that she does, and she can feel she is not alone. There is another presence with her, huge and imposing and pretty pretty scary. Is this the Gods? Are they here to judge her? Maybe she should have prayed more, Cersei ponders. Well, too late now.

Suddenly, a voice fills her head, imperious and kind, young and old, eternity and just a second at the same time. Then there are more - they tell her about her faults, her mistakes, one by one, until she wants to rip her hair out and weep. They talk her into shreds, bare her soul, until there is nothing left. When they have finally finished, there is a pause. She just waits, because what else can she do? Cersei feels every tiny part that is left of her is already bleeding, invisible drops on an imvisible floor. When the other presence doesn't say anything further, she finally feels pressed to add something.

"I - I am sorry."

There is no sound, and still she thinks they can hear her. It feels horribly inadequate, and she certainly isn't sorry for everything she did, but at least she is for a couple of things. She supposes in such a situation, an apology can't hurt.

"You are covered in fire and blood," the voice comments and Cersei grimaces (without a face) because that's just so Targaryen, "and there is somewhere you need to go."

Well, she's dead, isn't she? So it's not as if she can pick a travel destination, right?

"Where?" she still asks, because we'll, she's Cersei Lannister after all.

"Another world. Another life. To play a role in another game."

"That sounds -"

"We didn't ask for you opinion," the voice cuts her off, for the first time a bit haughtily, "its necessary. Just ... try not to ruin it this time."

Cersei has no idea what this is about and it would be great if someone, anyone, could inform her what is going on, but everything is already disappearing in a swirl of colours. There is red and gold and she thinks maybe grey and white, and then green and lots of blue and silver.

Cersei Lannister, child of Westeros and daughter of Joanna and Tywin Lannister, sister of Jaime and Tyrion, mother of Joffrey, Myrcella and Tommen, disappears.