Watch the headhumpers Rainbow!

She’s a cannibal!!!

@Marshal805 Because I’ve been a part of the Fluffy Pony community since the Ponibooru days. Some time ago though I learned of a third point of origin for Fluffy Ponies, besides Mixermike and the Green Text 4chan stories: There used to be an ask tumblr blog called Sweetie Poo, centered on a diarrheatic Sweetie Belle. Apparently in one post, she had taken a bath, and after drying off with a towel she became extra fluffy. That extra-fluffy Sweetie Poo became one of the three origins of Fluffy Ponies.
 
If it helps at all, when picturing Fluffy Ponies, especially if they are interacting with the Mane Six and other Equestrians, it helps if you picture them all as being extra fluffy Cutie Mark Crusaders, with some liberal doses of Chowder from the Cartoon Network Chowder show thrown in for good measure, in temperament.

@TricornKing  
How do you know all this?

That’s not Rainbow Dash, that’s Queen Chrysalis! That Scout is a Spy!

@TricornKing
 
I just got learned, so hard. I never did know of the root of the situation, so thanks.

HEAD CRAB!!!

@TricornKing
 
Woah.

@KennyC  
Well, like a lot of things that are at least partly horrible, fluffy ponies got their start on 4chan. There was a greentext story about MLP ponies being brought to Earth and lobotomized so that they could be remade into household pets. The story focused in particular on a depiction of Sweetie Belle as a lobotomized “pet” pony, with possibly fluffier fur added to increase her appeal.
 
At around the same time, Mixermike622 came up with Fluffle Puff, who as you can see is a rather silly pony who is incredibly fluffy. The two ideas coalesced and took off, with fluffy ponies becoming extra fluffy miniature ponies with Sweetie-Belle-style mentalities, sold by Hasbro as part of their MLP toy line. They quickly became parodies of the fact that quite often, Hasbro MLP toys have almost nothing to do with the original MLP cartoon series and properties. So for example, they became rather accident-prone, often dying in (literally) comical ways, one particular stable being “Fluffy + Something with Water = Fluffy Pony Drowned”.
 
This being 4chan though, the literal asshole of the internet, it wasn’t long before some 4chaners decided that they wanted to explore stories and art featuring fluffy ponies going through drawn-out deaths, maximizing the suffering and mental anguish the fluffy ponies went through before dying for their own enjoyment. To justify such abuse though, they began coming up with reasons why the fluffy ponies deserved it; they literally were walking fecal matter factories, they were selfish and cruel to each other, they were bratty and disobedient (in this case meaning one case of childish stubbornness or a tantrum from an otherwise perfect fluffy would warrant torture and abuse the likes of which would make a Guantanamo Bay guard vomit in disgust), they were worthless and had no purpose, etc. None of these things had existed beforehand mind you, they were just invented to justify the extended abuse and torture 4chaners would put the fluffy ponies through.
 
As you can imagine, Mixermike622 was not pleased by this development whatsoever. For a time, he even left the MLP fandom because he hated the fact that something he had helped create with Fluffle Puff, Fluffy Ponies, had turned into Saw-style torture gorn. Eventually he returned, but not without firmly entrenching Fluffle Puff as a solid resident of MLP:FiM’s Equestria, and thus not generally like the 4chan Fluffy Ponies.
 
Nowadays, with the move from 4chan to its own booru, Fluffybooru, Fluffy Ponies have developed considerably from when they were on 4chan. While the abuse is still there, there is often a backlash of content that balances it out. This non-abuse content ranges from “hugbox”, which is simply sweet and innocent pictures and stories of fluffy ponies (which coincidentally is what most people who aren’t familiar with the abuse side think of when they think of fluffy ponies), to what I call the “Mrs. Brisby and the Rats of NIMH/Watership Down/The Animals of Farthing Forest” genre: Essentially extended, multi-segment or chapter stories featuring fluffies trying to make it and survive in the world, coping with the fact that they are literally on the bottom of the food-chain in the world around them. These stories focus more on ferals or strays, fluffy ponies who either were abandoned by their human owners or who have for generations lived on their own without human “daddies” and “mommies” to care for them (as they were originally intended to be by their creator company, HasBio).
 
I hope this helps answer your question about where fluffy ponies came from.

@CodeLuxor  
Where can I get those?

That’s just her mane… does eating manes really count as cannibalism?

Where did fluffy pony come from anyway?

Taste the rainbow… conditioner

Taste the rainbow. Taken literally.