Special Friday the 13th Chapter, guys! This is canon, but is also a surprise for me getting over 2,012 views before January 13th.
Side note: Don't read if you're squeamish. Seriously, this made me cringe as I wrote it.

The rainbow-maned, cyan Pegasus fell into the darkness of sleep, the convoluted images following her during her entire descent.
She dreamed horrible things...angry, murderous things, things of darkness...
All of Ponyville was burning around her. The once-happy, thriving town was now awash in darkness, a blanket of ash covering Celestia's sun.
The buildings surrounding Rainbow Dash sagged in upon themselves, tired and strained from the ravenous flames eating away at their infrastructure.
As she walked amidst the ruins of her old home, the sounds of her hooves the only thing accompanying the burning, she cried, looking for her friends, the friends she had abandoned to sit on a cloud as all of Ponyville burned to the ground...
She walked to Twilight's tree library, its once lively and happy branches now on the ground, burning into ash.
Rainbow Dash looked around the premises for her unicorn friend, her eyes filling with tears as the acrid smoke irritated her already-wet eyes, tears of grief and pain obscuring her vision.
She tried to enter the building, but was stopped by the raging flames, the heat forcing her to back out. She was about to fly off and get a cloud when a clear path was cut by an unseen force, blowing her mane in its wake.
She walked through the path, and found her friend in the center, pinned down by a branch, the flaming limb almost splitting her asunder.
The cyan Pegasus got on her knees to mourn the her lavender, horned friend when the unicorns' eyes opened, revealing nothing but darkness.
Rainbow Dash reeled back in fear, but was held in place by the flames quickly surrounding her, the heat singing the frayed ends of her mane.
Twilight's carrion pulled itself through the branch, splitting the skin slowly, Rainbow's eyes held in place as organs spilled out, the intestines becoming unwound on the bough as she moved, forcing her strides to become halted as the long, slimy organ was unwound from her body, eventually falling in a heap under the pony.
As Twilight advanced towards Rainbow Dash, her stomach shaking with tension as it was pulled between the bloody heap on the ground and Twilight's distraught, walking carcass, she spoke, her voice full of fear and pain, bringing Rainbow Dash to tears as she watched her dead but living friend advance.
"Why didn't you come back for me? Don't you like me? Aren't we...friends? Rainbow Dash, I thought we were friends! Why did you leave me?"
Rainbow Dash stood on her hind hooves, trying to distance herself from her dead friend, tears leaving streaks of water as they finished their journeys down her cyan face.
"I...I didn't leave you! I would never leave you!"
Twilight's stomach stretched in tension, the heap of intestines behind her not unwinding, and started to split open, acid burning through the already charred floor. Rainbow Dash held down her stomach, panting wildly, her chest heaving.
"But you did, Rainbow Dash...you left me to die here!"
Rainbow Dash cried harder as her friend approached, the eager flames licking at her hooves.
"And now, you'll die too!"
Rainbow Dash jumped, her wings suddenly coming to life, as the unicorn dove forward, her stretching stomach splitting open, rolling as she hit the ground, drawing forward her other organs as well, screaming in pain and agony as the flames burned her body to ashes.
"Twilight, I'm...I'm sorry!"
Rainbow's vision fazed into darkness.
When it returned, she was outside of a destroyed Cupcake Corner, the door wide open, the darkness inside inviting her, greedily awaiting her rainbow mane, the beautiful decorations in shambles around the Pegasus' hooves.
She gulped, and walked in, the building bursting into flame behind her as she walked. She ignored the heat, slowly moving through the house, stopping to retch by the stairs as the image of Twilight's body filled her mind.
She moved up the stairs, one at a time, and arrived in Pinkie Pie's bedroom.
"Pinkie! You're okay!"
The pink party pony stood at the mention of her name, hooves at her side, normally poofy mane flat on her back.
"Uh, Pinkie?"
"Don't call me that."
Rainbow took a step back, the venom and hate in her friend's name stinging her more than the flames that mischievously crept behind her.
"W...what?"
"I said, don't call me that."
Rainbow screamed as her friend turned around.
"My name is Pinkamena Diane Pie, got it?"
Rainbow Dash's eyes widened as her friend's eyelids closed over darkness, patches of burned skin sloughing off as her jaw moved.
"What, have you forgotten all about me, Rainbow Dash?"
Rainbow shook her head, fighting to hold her bile down as more and more of Pinkie's face fell off, revealing the muscle and bone underneath, blood oozing from the uncovered veins and muscles.
"No! You're my friend, Pinkie!"
Pinkie laughed, but not with the usual, cheery sound, but rather with a sound of hate and misery, her jaw bones clicking, the joint no longer covered by skin or muscle to hide the sound of bone scratching bone, the cartilage seeping out in a molten slime.
"Right, your best friend...is that why when I cried your name, you turned over and went back to sleep? HUH?! Is that why, when I cried here, my body burning, my face falling off as I breathed and cried!"
Rainbow Dash hurled as the last of Pinkie's skin fell off, revealing charred muscle that strained and split as her jaw moved of its own free will.
"Pinkie, I'm sorry...I'm sorry!"
She raised her wings, preparing for flight as her deranged friend came closer, teeth stuck in a perpetual smile, her mane burning as she advanced.
"For what? Leaving me to die?"
"No, for...this!"
Rainbow kicked her best friend in the stomach, sending the walking dead pony into the flames, to her second death, and flew off, Pinkie's screams haunting her as her view once again fazed.
"You're leaving me to die, again? You'll die sad and alone, Rainbow Dash, just you wait!"
Rainbow opened her eyes to a depressed, burnt cottage, windows and door burst open, giving it a dead feel.
The sound of clops followed the cyan hoof steps, the burnt grass crushing beneath her.
As she walked, she began to notice that it wasn't burnt grass she was crushing, but rather the bones of small animals, their skeletons still writhing in pain from their gruesome deaths.
The Pegasus swallowed and pushed on, steeling her nerves for whatever the dark depths of the cottage had to offer.

Thus ends Part 1! Expect even more gruesome scenes in Part 2, which will come out this Friday! Any fan art of this scene will be viewed in the bathroom, so that I can throw up immediately.