WESTEROS AU XI: THE QUEEN BEYOND THE WALL

The sun resounds, like she's done ever,

in the great concert of the spheres,

and she completes her fulfilled journey 

amidst loud thunderclap and cheers.

She gives strength to the failing angels,

though they can't sound her core or may.

The undescriptibly high opus

remains sublime, like the first day.

Goethe, Faust. First words of Part I (my translation from the German).

This AU is Andersen's classic The Snow Queen in Westeros.
From Evenfall Hall on Tarth to the woods and ice caves north of the Wall, the story follows Brienne in her search for Jaime, who has been abducted by the Night's Queen, a legendary female White Walker.
Every chapter in the Swedish-language novella will open with some poetry, like the one above, for the First Story.

Dramatis personae

• Creators of the Mirror: Maesters
• Breakers of the Mirror: White Walkers
• Gerda: Brienne Tarth
• Kay: Jaime Lannister
• Gerda's Nan/Herself: Septa Roelle of Evenfall
• Gerda's Father/Himself: Selwyn Tarth
• Kay's Father/Himself: Tywin Lannister
• Kay's Sister (Lady Not Appearing in the Fairytale)/Herself: Cersei Lannister
• Snow Queen: The Night's Queen or Queen of North (female White Walker who married a Stark Lord Commander of the Night's Watch during the Age of Heroes)
• Erring Freakshow Troupe that Captured the Night's Queen: Themselves
• Springtime Sorceress: Melisandre
• Her Accomplice/Himself: Stannis Baratheon
• Flower Spirits: Stannis's Army (&) Stormlanders Burned at the Stake
• Wild Crow/Pet Crow: Edric Storm (Sir Not Appearing in the Series) (Margaery Tyrell, in the finale)
• Clever Princess: Renly Baratheon
• Clever Princess's Fiancé: Loras Tyrell (&) Margaery Tyrell
• Royal Family: The Tyrells
• Wicked Highwaymen: Brave Companions (Locke and his Cronies)
• Good Highwaymen: Meera and Jojen Reed, Bran Stark, Hodor
• Robber Maiden: Meera Reed
• Pigeon: Bran Stark as the Three-Eyed Raven
• Reindeer: Summer (possessed by Bran Stark) and Ghost (possessed by Jon Snow)
• Saami Woman/Shaman: Maester Aemon Targaryen
• Finnmark Woman/Shaman: Lord Commander Jon Snow
• Captain of the Black Betha (Sir Not Appearing in the Fairytale)/Himself: Davos Seaworth
• Surgeon on Board the Black Betha (Sir Not Appearing in the Fairytale): Himself

Opening Verses for the Chapters

First Story, Of the Night's Queen and the Maesters' Looking-Glass:

The sun resounds, like she's done ever,

in the great concert of the spheres,

and she completes her fulfilled journey 

amidst loud thunderclap and cheers.

She gives strength to the failing angels,

though they can't sound her core or may.

The undescriptibly high opus

remains sublime, like the first day.

Goethe, Faust. First words of Part I (my translation from the German). 

Second Story, A Courtier Boy and a Gentry Girl:

Say which day

does a young child cease to be a child?

Say which day

is a young child's friend no more a friend?

Say which day

does a person lose those good rights

to safety, solace, and grace?

Say which day

is one regarded as coming of age,

and must keep tears off the face?

Barbro Hörberg, "Gamla älskade barn" (my translation from the Swedish).

Third Story, The Heretic Burnings of the Priestess Endowed with Powers:

She looked over his shoulder

For ritual pieties,

White flower-garlanded heifers,

Libation and sacrifice,

But there on the shining metal

Where the altar should have been,

She saw by his flickering forge-light

Quite another scene.

Barbed wire enclosed an arbitrary spot

Where bored officials lounged (one cracked a joke)

And sentries sweated for the day was hot:

A crowd of ordinary decent folk

Watched from without and neither moved nor spoke

As three pale figures were led forth and bound

To three posts driven upright in the ground.

The mass and majesty of this world, all

That carries weight and always weighs the same

Lay in the hands of others; they were small

And could not hope for help and no help came:

What their foes like to do was done, their shame

Was all the worst could wish; they lost their pride

And died as men before their bodies died.

W.H. Auden, "The Shield of Achilles".

Fourth Story, The King and Queen of the Reach:

She didn't fall being so careless:

a demigod of royal name,

came down, just like a golden downpour,

onto the young maid of good fame.

With modesty within her bosom,

yet stature- and countenance-proud,

she went off to court, to encounter

the cold, piercing glares allowed.

The guards, the pageboys, and the courtiers

stood there, dazzling candles so tall,

and on the lace frills of their cravats

the curls of allonge wigs did fall.

The court ladies, dressed for the gala,

they curtsied the best to appeal.

And the maidens curtsied the lowest:

here, power was true and was real.

The worship of the royal lover

was made known to his entourage.

That "strength renders tribute to beauty",

was drawn with his and her visage.

Carl Snoilsky, "Aurora von Königsmarck" (my translation from the Swedish).

Fifth Story, The Little Greenseer:

At evening, when the stars had just begun

To move along the edges of the hills,

Rising or setting, would he stand alone,

Beneath the trees, or by the glimmering lake,

And there, with fingers interwoven, both hands

Press'd closely palm to palm and to his mouth

Uplifted, he, as through an instrument,

Blew mimic hootings to the silent owls...

William Wordsworth, "The Boy of Winander".

Sixth Story, The Maester and the Lord Commander at the Far Side of the World:

Follow me beyond the mountains, beyond cool and tranquil rivers,

where the oceans slowly fall asleep in rock-beds that slope down...

Somewhere there, beyond the heavens, there's my home, and there's my mother,

in a golden mist she's hidden, made of roses is her gown.

May the dark and salty waters soothe my cheeks, ablaze with fever,

may we be miles away from this life when night gives way to morn...

I was not from this world, and, due to my restlessness and passions,

I have gone through endless suffering, and pain, and woe, and scorn.

Dan Andersson, "Omkring tiggaren från Luossa" (my translation from the Swedish).

Seventh Story, What Happened in the Ice Cave Beyond the Wall, and What Happened Afterwards:

Everything that shall end

is but a clue.

What cannot be reached

does here come true.

What cannot be described

is here made real.

The eternal feminine

leads us to feel.

Goethe, Faust. The last words of Part II (my translation from the German). 

Canon divergences

• In a memorable scene, Brienne wounds Jaime in the side, causing him to fall unconscious, with a piece of dragonglass (she got it from Jon Snow), when they reunite in a glacier north of the Wall. So Jaime and Brienne have wounded each other in the side, she thinks she's killed him, a frozen teardrop of hers falls between his lips and her warm blood stains his hand and wound... he swallows the teardrop, and he comes to, still pale, his eyes shifting from ice-blue to their usual green colour... (cathartic indeed!)
• Jaime has his hand cut off by Loras Tyrell on the homecoming to Tarth, as both leading characters are banned from the Reach and blamed for Renly's death at Storm's End (he tries to make peace between Loras and Brienne à la Mercutio).
• Since Jaime's character arc is different from canon, Bran became hemiplegic when he accidentally slipped from the walls of the ruined tower at Winterfell.

Lastly, there is a relevant hypothesis at the end...
In the original fairytale, when Kay and Gerda return home, they find Nan reading the Gospel of Matthew. In my AU, Jaime and Brienne find Septa Roelle reading a hymn to the goddesses (Maiden, Mother, and Crone) of the Faith of the Seven... which is, coincidentally, the last stanza in Goethe's Faust Part II... which acts, like the Lutheran hymn "Roses grow and fade away" in the original tale, as the leitmotif and the coda.
Therefore, it is implied that the World of Ice and Fire is either Earth in the future or a planet colonized by humans from Earth (could it be?)