"Rainbow Dash!" Twilight called from the ground in front of Rainbow Dash's mansion in the clouds just over Ponyville. "Rainbow Dash!"
A tired-looking Rainbow Dash poked her head out the window of her bedroom.
"Whadya want, Twilight?"
"An explanation. Can you please come down here? I don't wanna shout everything I say!"
Rainbow Dash groaned, threw off her pajamas and flew down to the earth, sleep still in her eyes.
"What is it?"
"Apparently you kept Spike up all night with one of your bedtime stories."
"Well, what can I say? I'm just really good at storytelling."
"A little too good," Twilight replied snidely. "I have been trying to get Spike to be less...I don't know, lazy about getting up in the morning and not sleeping in until nine in the morning, and your horror stories about some slender dude is interfering with my efforts."
"Slender dude? Oh, you mean the Slender Mare? Spike really got a kick outta that, didn't he?"
"I won't let Spike join you and the Cutie Mark Crusaders for your occasional sleepovers if this is what I'm gonna get every time."
"Okay, okay: no more Slender Mare - or any other scary stories."
"Thank you."
Twilight turned away for a few steps before she stopped herself and cocked her head to see Rainbow Dash behind her.
"What could you have possibly have told him to scare him so stiffly, anyway?"
"Beats me," Rainbow said earnestly. "Slender Mare's not even that scary."
"Oh, really?"
She nodded enthusiastically. "Totally. I mean, he's a little scary...well, I guess it's not too surprising, with Spike being a baby dragon and all."
Twilight's literary curiosity got the best of her. She turned completely around.
"Mind filling me in on what happened last night?"
A wicked expression grew on Rainbow Dash's face. "So, Twilight wants to hear the legend of the Slender Mare, huh?"
"Well, yeah, I-I guess."
Rainbow lit up. "Great! Just meet me in my cloud house, and- oh, wait, you can't walk on clouds."
"Sure I can!" Twilight exclaimed. "I cast that spell that lets us walk on clouds, remember?"
"Oh, yeah."
Twilight's horn lit up, and a bubble spontaneously erected around her. She carried herself up and landed herself on the surface of Rainbow Dash's front yard, the bubble popping upon contact. It felt soft against the soles of her hooves, like she was walking in a field of especially soft and fluffy pillows. Rainbow Dash met her at the front of her house and led her inside.
"So, tell me about this Slender Mare guy," Twilight said when she and Dash were on a couch in her living room.
Rainbow cleared her throat.
"Every night, at ten past two, the Slender Mare rises from the shadows of the night, in search of his next victim. He stands six feet tall, and is distinguished by his undeniably long and crooked hooves and neck. He bears no face, but simply two ears perked on his head, forever in search of the slightest sound which might lead him to his prey. He wears a fine suit of black to disguise himself as a lone shadow prowling the quiet growns of Ponyville. In his hooves he bears a book with no cover and no title-"
"Wait, why would he be carrying a book with no cover and no title?" Twilight interjected.
"I am getting to that!" Rainbow Dash snapped.
"Oops, sorry. Continue."
She cleared her throat again, to resume her ominous storytelling voice.
"The book he bears contains the names of his countless victims. Every night, he writes down another name. And if it's yours, it means he will be coming for you. He spends his days incognito, as a shadow in a dark alley somewhere in Ponyville, where he can hear the names of everypony who willingly wanders by, learning more faces with each passing day. When everypony's asleep, he steps out from his hiding place, and begins his silent search for his befallen prey.
"The Slender Mare is a phantom: the only object he can carry being his own book of innocent victims who lost their lives to him. But he does not need grasp to aid in his plight. When he finds the next pony he seeks, he extends his two long arms from his back, and plows them into your chest, and sucks your soul clean out of your body, leaving only a small pile of ash in your wake.
"Even if you think staying up will help you avoid the Slender Mare...you're wrong. For if you do, he will get you, anyway. His unoccupied hand will cover your mouth so you don't scream while he sucks out your soul. And don't even think about trying to leave town. He does not need to walk. Don't go forward. Don't turn around. For the Slender Mare could be right behind you, or right in front of you the moment you turn your head. Don't look him in the face, and don't open or close your eyes.
"The Slender Mare cannot be killed, either, since he's just a walking cloud. They say the only weakeness of the Slender Mare is to collect the five missing pages of his book. One fateful night, a strange wind blew and discarded five pages of the Slender Mare's and scattered them around town. If you collect all five pages, the Slender Mare's completed book will send him back into the void of night where he came from. That is - the Slender Mare doesn't get you first. He's everywhere. All at once. And you never know where he will appear next."