Chains, written by BookyBrony, is an Alternate Universe Fic set in the My Little Pony: Friendship Is Magic universe where humans exist in Equestria, but there's one major catch:The humans have become enslaved by the Equestrians.Indeed, for reasons unknown even to ponies today, humans have become a source of slave labor to their pony masters, being either used for basic hard labor or as a status symbol.The story centers around one human boy in particular named Chains, who started out just before being bought by the parents of one (then filly) Twilight Sparkle, and was assigned to be her personal servant. However, the story focuses on how the slave boy Chains and the friendship he forms with his said Pony mistress which gets progressively stronger as the years go by.Can be found of Fanfiction Dot Nethere and Fim Fiction Dot Nethere.
This Fanfic contains examples of:
After the End: In chapter 15, humanity is implied to have nuked itself back to the Bronze Age.
Darkfic: Actually mostly subverted, because despite the dark twist placed on the humans, the fic mostly follows the MLP canon to a reasonable extent, to the point where Equestria could be looked upon as a Crapsaccharine World merely from the humans' point of view.
Dirty Business: Not a day goes by that Celestia doesn't regret her part in mankind's enslavement. She's seen weeping over it at several points and she can't even look Chains in the eyes because he reminds her of the human ambassador she betrayed, telling him that she feels ugly when she does. It's eating her, but she stands by her decision...
Easily Forgiven: Zig-Zagged; Luna is willing to forgive Celestia for imprisoning her in the moon for a thousand years, but she's clearly not happy about the whole Slave Race thing.
Even Evil Has Standards: When Nightmare Moon saw Chains for the first time and found out he's a slave, she was actually somewhat disgusted by it, and this dislike still sticks when she's restored back to Luna.
First Time Feeling: Happiness, for Chains, when Twilight treats him like a friend, rather than property (or worse). He smiles for the first time ever.
Follow the Leader: There's now a ''Humans Enslaved by Equestrians" group on FIMmFiction.
For Want of a Nail / In Spite of a Nail: The presence and enslavement of humans has obviously changed the overall world and backstory drastically, but so far the Nightmare Moon arc largely follows canon.
Happiness in Slavery: After he was bought by Twilight's parents, Chains has shortly developed a strong friendly relationship with Twilight and her family, and is well appreciated for his work.
Lawful Stupid: Celestia allowed the enslaving of an entire species rather than defy the council, because she was worried that if she overthrew them she would become a tyrant. This despite the fact that slavery is about as tyrannical as it gets.
Lured Into a Trap: Celestia invited Prince Tanelon over the day after she signed the enslavement order.
May double as Line-of-Sight Name since she got the idea from seeing the chain-marks on his wrists.
Mismatched Eyes: Of the Shared Unusual Trait variety. Chains looks so much like the Prince of the Azure Dawn that Celestia can't look him in the face without her guilty conscience tormenting her.
My Species Doth Protest Too Much: It turns out that not every pony in Equestria accepts the humans' enslavement. Pegasi are largely abolitionists; it's mentioned that many pegasi boycott businesses that use slave labor, and Rainbow Dash is even somewhat hostile towards Twilight when they first meet because of this; after she ran her over, she was determined to have nothing to do with Twilight-until she found out Chains can read. Applejack has human twins working on her farm, but they don't wear slave collars and she even considers them unofficial members of her family. She also mentions (quite proudly) that the Apple Family has never had much use for slave labor.
Fridge Brilliance kicks in with the pegasi when you remember they mostly live in (literal) cloud cities where humans wouldn't even be able to go. Even though cloud walking spells do exist, only unicorns can cast them and they are only temporary. In addition, even with such a spell humans wouldn't be able to work the weather, which makes up by far the majority of the pegasus ponies' industry. With their inability to function in a practical role and the sheer impracticality in even attempting to keep one as a status symbol, pegasi have no real cultural bias to be pro-slavery and can view it more objectively.
Even more Fridge Brilliance is that the pegasi could be considered Equestria's equivalent to the industrial working class next to the earth ponies' agricultural and unicorns' upper/aristocratic classes. Abolitionism flourished in the wake of industrialization.
Also, Luna is not at all happy to see what her sister did.
Mundane Utility: Rarity mentions that she'd like to purchase a human, but not for the status symbol they would give. She just thinks it'd be nice to have some help around the shop.
Reasonable Authority Figure: Contrary to what some people might think, Princess Celestia remains basically as reasonable and benevolent as she is in the MLP canon, even allowing Twilight to bring Chains with her when Celestia offered to personally tutor her. And while it is clear that she did allow for the enslavement of the humans, it's quite clear she took no pleasure in it and she can't look Chains in the face because he reminds her of the Prince she betrayed.
Twilight could be considered this as far as being Chains' mistress and Spike's boss goes.
Some humans are so ill-treated by their masters that they go insane.
It is also mentioned that humans were used in gladiatorial fighting rings for the public's enjoyment, but some pegasus abolitionists were able to stop the practice. Underground fighting rings still exist, though.
What the Hell, Hero?: Luna is none too pleased to find out the humans have been enslaved, and accuses Celestia of having been too weak willed to execute her Deadly Decadent Court as its cause. When Celestia also refuses to make slavery illegal immediately, Luna only has more fire to her anger.
Also occurred in the comments after Chapter 15, due to the reveal that Celestia was so quick to suggest slavery and doesn't appear to have made any effort to improve the living conditions of slaves. One commenter described her failure to do anything like this: "It's less like rushing into a burning building and more like stopping the arsonist from starting the fire in the first place. Celestia hasn't even been walking, she's been sitting for 300 years. By now the fire has spread and the house and rest of the town have already burned down."