Creeping Darkness

A cross-over fic between Alan Wake and My Little Pony Friendship Is Magic.

There is a shadow to all of existence, a place that all worlds are shielded from by a thin veil. A Dark Place, where a single presence plots and struggles to consume all creation with its darkness. The author Alan Wake is one who has defeated this Dark Presence, but to save his wife and his world Alan had to remain trapped in the darkness.

Now, through his struggles to return to his wife, Alan has unintentionally released the Darkness and an old villain upon Equestria. To fix the mistake, Alan starts a new story with Twilight Sparkle as the protagonist. Can the unicorn find the strength to face the darkness, or is all of Equestria doomed to be the victim in the dreadful horror story?

Can be read here. Can be enjoyed without actual knowledge of Alan Wake.

Tropes used in Creeping Darkness include:

Alternate Continuity: To the authors' later My Little Pony Friendship Is Magic Fanfic Past Sins. Both stories share the common element of Nyx, but are otherwise completely unrelated to each other.
Author Avatar: Sort of. To summarize the first chapter in a nutshell, Alan Wake is suffering from writer's block and gets fascinated by My Little Pony Friendship Is Magic, becomes a brony and then writes fanfic about it. Does that sound familiar? And then if that was not enough... He writes himself into the story as a pony. All this is done realistically and completely in-character.
A Bloody Mess: During a fight, Twilight gets hit in the back of the head with something and feels a sticky substance dripping down the back of her neck. She fears it might be blood or even brains, but when she goes to check, it's just grape jelly.
Crossover: Between My Little Pony: Friendship Is Magic and Alan Wake.
Darker and Edgier / Lighter and Softer: A bit of both. Being a crossover, Creeping Darkness is much darker and edgier than My Little Pony Friendship Is Magic, but at the same time, is much lighter than Alan Wake. Alan even Lampshades this when pointing out how innocent and childish Equestria is compared to his universe.
Dark Is Evil: A trope carried over from Alan Wake. However, night is not evil, only the darkness it brings.
Death Is Cheap: By the end, Twilight ends up dying... temporarily.
Earn Your Happy Ending: Not only did Alan manage to end his story on a happy note, but it's hinted that he has gained the inspiration to finish "Return".
- Also, Everybody Lives. Not even Nightmare Moon dies... sort of.
Enemy Without: Nightmare Moon is treated as this, and has her own Friend Without in Nyx.
Film Noir Narration: It's Alan Wake, it comes with the territory.
Frying Pan of Doom: Applejack's weapon of choice.
Light'Em Up: Twilight's main weapon is her ability to use magic to create light.
Lock and Load Montage: Alan Wake gets one as a pony. Then he immediately trips over his new body.
Only Mostly Dead: They're not dead, they're Taken. Getting them back won't be easy, though.
The Power of Friendship: Used both for creating giant laser beams and making friends.
The Power of the Sun: Celestia has this. And because the narrative calls for it, it still doesn't save her.
Troperiffic: Creeping Darkness is very self-aware. To start off it's about Alan Wake, a thriller novelist, becoming a brony and writing My Little Pony fanfiction - all while trapped in The Dark Place. Alan explains certain narrative devices that he has to use in order for the story to "work" and be contiguous with its own logic. At the same time he tries to keep things as light and fluffy as he can in order to keep the innocence of the protagonist and in-universe setting.
The Worf Effect: Justified and in-universe. The two strongest characters with the highest chance of being able to defeat The Darkness all on their own ( Celestia and Luna. The former having the power of the very sun itself!) are defeated off-screen at the very start of the story. Alan Wake Lampshades this as being necessary for a horror story, which is the only kind of story The Darkness would allow. He states that unless the protagonist is put in a bleak and hopeless situation then it just wouldn't be horror.

"Any good horror story requires that the protagonist be out gunned, over powered. The reader has to believe there is an honest chance the story will end poorly, as some horror stories do. The situation needs to be almost hopeless. If the protagonist could fight back and have a good chance of victory, then it wouldn’t be a horror story. It be a fantasy story or adventure novel."

What The Hell, Author?: Delivered by Rainbow Dash to ponyfied Alan Wake after he enters the story to try and help out Twilight and the other ponies. Given that Dash thinks that Applejack, Rarity, and Pinkie Pie are all dead or worse, it's somewhat justified. And his words to her, Fluttershy, and Twilight only make it worse:

"This is all happening because I brought you here."