Applejack is a shell of her former self, a broken soul barely bound to the land now. Her front legs are severely scared after they were pinned down from the burning rubble of her home, after trying to rush in to save her family. She didn't mean to start the fire, she didn't mean to kill her family, it just happened. She managed to get the burning support beams off her front legs and dragged each pony by the scruff of their neck out of the home. Big Mac and Granny had died from suffocation, but Apple Bloom, poor, sweet, small Apple Bloom, was impaled by the caved-in roof. She was still barely alive when Applejack pulled her out, the large chunk of wood still sticking out of her back, having severed her spine, paralyzing her hind legs. Her little sister was suffering, she had to help her. With a couple quick and strong kicks, her head caved in and ended her misery. She wears the garments of her deceased family now, and in grief and guilt, tore out one of her eyes. Rarity and Twilight used their magic to try and heal her eye, but now all that's left is a floating iris and pupil in a void a black, no sclera, and half-blind in that eye. She wears Big Mac's yolk, Granny's neck wrap, Apple Bloom's bow, her dad's hat, and the two turquoise hair bands her mother used to wear. She chopped her mane short but kept her tail long to wear the bow and wrap. Her cutie mark changed with her mind, and now carries an apple mark for her siblings.
Pinkie Pie —
A break down taken too far, gone wrong and twisted, with thick magic in the air of Equestria, her mind split in two, but not her body, to some degree. One head sinister and sadistic and evil, the other, sad and pitiful and submissive, but not masochistic. The evil one bites the pitiful one and scratches with the specialized metal claws at what remains of the pitiful one's body, leaving deep scars. Pinkie Pie's previous happy and bubbly personality left some remnants of itself behind, with coiled springs in the front legs of the pitiful's body, showing she once had a "spring in her step." While the evil one controls the back of the body, using her hind legs with fake claws to scratch at the pitiful and her ears, she doesn't control the front legs. If she wishes to go someone, the pitiful one listens and obeys her commands, but when she tries to be resilient and stand up, she gets bit and clawed at, and the evil one stands up on her hind legs to walk to a wall to smash the pitiful one into. With how cruel the evil one is, she often attacks anyone, and once tore the wings off of Rainbow Dash, attaching them to a harness to wear. Her cutie mark changed to show the physical and mental split of herself.
Rainbow Dash —
Even faster than before and still loyal, but now bitter and more snarky than before. Once Pinkie Pie had stolen her wings, ripped them straight off of her back with teeth and claws, they get into many physical fights. Dash tries not to hurt the pitiful Pinkie's head, and the pitiful one returns the favor. Her body is covered in scars and bite marks from the brawls with the evil Pinkie, but oftentimes the fights come out as a draw and end very quickly. When her wings were ripped off, Twilight kindly gave her wings to Dash, and so did Fluttershy and Scootaloo. With now 3 pairs of wings, she is faster and more dynamic than before, but now is hindered to flying at shorter times due to residual pain from her previous injuries and the new wings, having phantom limb pains, even though Twilight's wings are now in place of her lost ones. She is oftentimes seen stuck on a cloud, unable to fly down due to the unbearable pain, stuck there for hours, sometimes a few days, so now she is often found on the ground, not flying too high up, in fear of losing control of her wings and crashing down into the earth. Her cutie mark changed to a dark thunder cloud and the lighting bolt having the colors of those who gave their wings to her.
Fluttershy —
After the whole situation of turning into a vampire bat pony, and having it "fixed," some of the traits, habits, and addictions were left behind. Over time they slowly became more apparent in her head and appearance. Being around animals all the time mixed with what was left of the vampire bat and, similar to Pinkie Pie, the magic in the air, it slowly started to transform her into a beast. Vampire fangs became of breed of vampire and venomous snake fangs, a long fluffy wolf's tail replaced her once long and flowing pink tail, hackles line her back and long tufts of thick fur grew from her ears. Her nose became that of a goat and grew two long horns from her forehead. Her lean muscles from always working with animals and gardening grew a little stronger with different animal's DNA being introduced into her body via magic. Discord tried to help her, to reverse what was happening to her or to try and stop it or slow it down, but the magic fused and struck them both. He became feral but still was protective of Shy, and she gained some chaos magic. She still has some civilization in her, but at times she loses control and goes on hunting sprees and attacks anyone on sight, even her own friends, though, as a group, they can somewhat contain her until she comes back to her mind. Her cutie mark is butterflies with spiked and curved wings like the Flutterbat cutie mark, and with darker colors.
Rarity —
Still elegant and sophisticated, she only changed slightly when the Nightmare version of her seeped in from an alternative universe and slightly possessed her. Her coat became darker and her mane took on a slightly blood-red gradient. She's still the diva she was, but now she's the cruelest of all the main six, knowing just how to pluck at someone's heartstrings and pick apart the psychology of their thoughts, manipulating them and mentally and emotionally torturing them, and at the perfect moment, striking and bringing them to the brink of insanity with physical torture. But don't worry, she's still a lady, and a lady wouldn't hurt innocent creatures, just the ones that deserve it. Applejack and Twilight came together at her request to build her a pair and metal wings, to look elegant and princess-like. Twilight and her wrote a spell together to allow a period of time for the wings allow her to fly. Rarity has to cast the spell for it to work, but over the course of the spell being active, it slowly drains her energy, so she can't always fly. And yes, her garters and stockings are made from genuine leather, she won't tell from who, but she does say it was "kindly donated by one of her victims." Her cutie mark became more detailed with highlights and shadows to the gems, with a blood-red gradient at the bottom of the mark.
Twilight —
Having given her wings to Rainbow Dash, she, Applejack, and Rarity came together to build her a new pair of wings. Using the original blueprints for Rarity's wings and modifying them. They came up with a design that used a special type of crystal alloy for the "feathers," Chrysalis's throne, and King Sombra's crystals that grow from his magic. The alloy was infused with the magic from Twilight and the stolen horns of Luna and Celestia, making the alloy stronger and filled with even more powerful magic. These wings don't require a spell-like Rarity's do and simply work almost like normal wings, the only difference being they're not real feathered or webbed wings, and that they are faster, slicing through the air with their sharp angles, and the infused magic giving her large boosts of speed. When Luna and Celestia tried to retire, Twilight felt left behind, treated like a filly until they left her in charge suddenly like an adult, giving her no rules, no instructions, no notes or tips or tricks or good lucks, just put her in a crown and throne and abandoned her. So she abandoned their bodies in Tartarus, living in constant, writhing pain with snapped off horns, torn off wings, and constant electric collars around their necks and legs, singeing the fur off of them and scaring their flesh. Twilight performed a very long surgery on herself to implant their horns into her skull and giving their magic to her. She is the most powerful being in Equestria now and no one dares oppose her after she displayed what had happened to Luna and Celestia, and what will happen to those who dare threaten her and her friends. When she gained the Alicorn sister's horns, the magic overwhelmed her body so much that one of her eyes now permanently glows white and her other eye is now shaped into her cutie mark symbol, her wide-eyed stare sends chills down the spine of those who make eye contact with her. Her hair is cut much shorter now and she often gets nose bleeds. A large gem is embedded into her upper chest, lower neck area, glows the color of her magic. It is the same crystal alloy of her wings and is a way for her to store more magic and have more control over her magic. When anyone stares into the gem for long enough, they start to see swirls of magenta magic inside, mixing with yellow, blue, bright neon green, red, and black and purple bubbles of magic, the stolen magic of Celestia and Luna, Sombra's Crystals and dark magic, and Chrysalis's throne's magic. The large amounts of magic in her body transformed her hind legs into extremely sharp, knife-like appendages. Her cutie mark changed to have the 5 white stars that encircle the larger star to be the colors of her friends, the main star having a dark gradient at the bottom, and the white spikes behind it now black.