A Mighty Demon Slayer Grooms Some Ponies is a My Little Pony: Friendship Is Magic fanfic by DGD Davidson, about a girl brushing the manes of cute ponies. As this premise would imply, the story is serious, dark and moody.The story is a exercise in Canon Welding of G1 and G4 of My Little Pony. It stars Megan, the Kid Hero of G1, several years later as a troubled high-school girl who is trying to forget about her past. But the past comes knocking in the form of six ambassadors from Equestria; five thousand years have passed in Ponyland, and the small population from Dream Valley has blossomed into the empire of Equestria. The ponies now want to make contact with the human world, and they figure out that the best way to reveal themselves is to enter a horse show (because that's where you show ponies, right?). Of course, they need to be properly groomed, and who's a better choice than the legendary Magog the Mighty (Megan) and her siblings, Moloch (Molly) and Danel (Danny)?Megan herself, though, is not happy about being reminded of her time in Ponyland, which wasn't exactly sugar-sweet...While originally inspired by the Bathtime for PoniesWAFF series, it has since grown into a serious, Darker and Edgier interpretation of G1.
This fic features the following tropes (note: only these unique to this story, not the original G1 My Little Pony):
Adult Child: Surprise, running away from Wind Whistler's compulsory military service and preferring to play with Danny all day.
Bad Dreams: Megan mentions having nightmares for months after facing (and killing) Tirek. She was, after all, just a kid.
Becoming the Mask Grogar admits to a minor case of this. He seems to shake it off however
Complexity Addiction: For Tirek's plan to succeed, he needed to wait for the rainbow bridge to open again, take the elements to Earth to subvert their power to have a superweapon ready, unleash Hell on Earth in Equestria and hope his mother actually shows up, all the while posing as the good guy so no heroes thwart him before he is ready. As it turned out, it took 5000 years for the bridge to re-open. Any sensible person would probably abandon the plan after a couple centuries, but Tirek really wanted his revenge.
Deconstruction Fic: The story explores just how would a Kid Hero's youth be affected by being forced into the role of a monster-killing hero and into a mother figure for an entire species (and being forced to Shoot the Dog a couple of times).
Disappeared Dad: Megan's father, whom she idolized, ran away with another woman. Serves a catalyst for a lot of resentment.
Does Not Like Men: Megan, because of her father. She is particularly harsh toward the Big Brother Ponies and Danny and some of her statements show her to have an Irrational Hatred of them. Finally, she becomes verbally and physically abusive to Twilight after mentioning she has an interest in a boy (Flash Sentry) and tries to defend him from Megan's insults.
Friendless Background: Megan. It's hard to make friends when everyone else's interests seem to revolve around boyfriends, fashion and the like, instead of farm work (and Saving the World.)
Gambit Pileup: the whole of G1 and G4 turns out to be a single one between Majesty, Tirek, Grognar and G1 Twilight
The Ghost: Megan's mother. She's mentioned a couple of times, but she is never seen (not having time for her children after her husband had eloped).
Humanlike Animal Aging: Zig Zagged. In the ancient era, Ponyland's ponies age like horses (a pony remarks about an eleven-year-old human that it's "two in human years"). Over the next several thousand years (by the Friendship is Magic era) they become much more humanlike, including a human lifespan.
I Did What I Had to Do: Megan still isn't happy about many of the things she was forced to do as a protector of Ponyland and even says the phrase at one point. This also includes killing Wind Whistler before she could become a tyrant.
Insistent Terminology: After getting fed up with Wind Whistler's increasingly draconian policies and refusing to acknowledge their crippling claustrophobia in work assignment, all of the Twinkle-Eyed ponies go on an exodus northward (and it's implied they would become the Crystal Ponies). Afterwards, whenever the Twinkles were mentioned around Wind Whistler, she would only call them "the deserters" and demand others do the same.
Last-Second Word Swap: Molly just barely stops herself from telling Fluttershy about a horse that they had to put down, instead saying that he was put... into a retirement home.
Literal Split Personality: All the ponies created by Queen Majesty were representations of various aspects of her personality. This is also why she created so few males.
Nice Job Fixing It, Villain: As a side effect of maintaining their ruse Tirek and Grognar gave Equestria a couple thousand years of prosperity. For all their villainy they seem to be more efficient at good than evil.
Promoted To Parent: Deconstructed by Megan taking on so much responsibility for Danny and Molly after her father's disappearance that she can't relate to them as a sibling anymore. Her mother is technically still around but is too busy running their farm to even be seen in the story.
Revenge Before Reason: Tirek spent 4500 years pretending to be a benevolent ruler, just for a chance to get his revenge
"The future of two worlds depends on you having a well-brushed coat!"
Shown Their Work: The author made sure to research horse grooming in order to depict it accurately.
Shrouded in Myth: Megan (and Molly and Danny) are remembered in Equestria as godlike warriors rather than the ordinary people they actually are.
The Spock: Wind Whistler, being the ponification of Majesty's logic. Deconstructed, as her intelligence gives her an incredible ego, and her disdain for emotions drives away most of her friends. Eventually, viewing feelings as irrelevant, she eventually plots to throw a coup and conquer everything beyond the Dream Valley.
Straw Hypocrite: Turns out, Wind Whistler, viewing herself as infallible and wanting to force the world to be like her.
Wind Whistler: If I am to build my empire of love and tolerance, I cannot tolerate someone who will not share my vision, even if that someone is you [,Meghan].
Take Our Word for It: After Megan casually mentions how she had to euthanize her favorite horse because he broke his legs in front of Fluttershy, she hits Megan with The Stare. It was so intense that she blacks out instantly and wakes up in a pile several hours later.
They Would Cut You Up: Megan has a nightmare about this happening to the ponies (complete with a German-speaking Mad Doctor), even after Danny persuades her that "vivisecting friendly talking animals only happens in dumb sci-fi cartoons".
These Hands Have Killed: Megan feels lingering feelings of guilt after having to put down her favorite horse T.J. after he snapped his legs, especially after she's visited a world where horses are every bit as sapient as humans. But this pales compared to her feelings after killing Wind Whistler in self-defense after Whistler judges Meghan a threat to her vision for her empire. Megan continues to have nightmares for years.
Uncanny Valley: invoked The twinkle-eyed ponies' faces, due to their unmoving eyes.