Pestilence rode in to Purgatory at a steady pace while clad in long white robes that sought to hide her appearance beneath, just like she had done an infinite number of times before. She rolled her weight effortlessly in time with her mount's motions as he brought her to the main area filled with lost souls. To the eyes of everyone else her horse was shining white and glorious aside from the rolling spots of plague and decay, bloated pustules of greenish-yellow liquid that threatened to burst and spread their foul effects. The steed's lips had begun to rot away and reveal yellowed teeth, the brittle bone already chipping away from the ravages of time. It wasn't until she dismounted and began to peel away the bit and bridle, the saddle and stirrups, that the illusion melted away and revealed the truth hidden beneath. Her 'horse' was a man, naked as the day he was born and the blackened marks of his sins etched upon his right cheek.
Pestilence was a caring woman and her movements showed compassion as she released her companion to the care of the imps that had gather around. He had served her for many years and it was time to let him free, even if his servitude was merely the minimum she required of him. She and her sisters all had their own ways of choosing their steeds but perhaps for the male she had crossed to close to the ideals of War. He had been stubborn and aggressive until finally she broke him, but even still he never fully committed to his role and harbored thoughts of misbehavior from time to time. It truly was difficult to find a worthy soul. It was only by this point that the forgotten prisoners of this plane were allowed to come closer, finally revealing the extent of her appearance.
As Pestilence turns towards the encroaching crowd and steps forth more details can be made out. She is clad in
flowing white and sickly yellow, color faded as from age and weakness that seems to seep decay in every essence. Despite this her figure is decidedly feminine as the fabric shifts and clings to her generous curves as she walks with a slow, swinging, gait. A crown adorns her head, golden yellow and tarnished, while a thick white veil hangs over her face only hinting at the outline of what lies beneath. Where her eyes should be are instead filled with two brazen orbs of yellow light, tinged around the edges with shades of green and brown like dying plants or fungus. As the lost souls push nearer they can all feel a fetid inner warmth as if coiling vines of sickness twist and writhe within their flesh, perhaps the only sensations they have felt in a long time within this place.
Her glowing eyes sweep over the begging crowd, lingering on individuals for mere moments as their lives are laid bare within her mind. She could know everything they did and exactly why they had been dumped here instead of burning in Hell or ascending to Heaven. The problem was that most of these souls were too eager, their desperation driving them forward without concern or care for the intricacies that the rider of disease truly worked with. On the other hand she needed someone who would not prove too difficult or stubborn like her last horse has proven. The individual needed to balance in-between in order to be the most effective, though in truth she was far from concerned with time. Contagion was a slow and insidious killer, patience was something she had in spades.
Perhaps fate was the true guiding force behind the series of events that led the woman to stumble forth and fall to Pestilence's feet, the otherworldy being slowly turned her gaze downward to take in the measure of the blonde woman before her. After precious few moments her glowing eyes illuminated even brighter, shining with interest as she watched the meticulous nature that she had worked with bacteria and other microbial substances in life. This one had potential far beyond what she had settled for in the past and the rider could not pass her by. She was not willing to be certain, but that was of no concern to her. From behind the white veil her feminine voice rolled, her words carried wet squishing sounds and faint traces of gurgling but she was still perfectly understandable as her tone carried the unmistakable weight of absolute authority.
"Morgan Sommers. You have helped and harmed in equal measure now haven't you? Your fascination gave you purpose, yet in the end you died of a sickness beyond your means of curing. How delightfully ironic."
All around them the eager souls began to whisper as they knew their mistress had already made her decision. There was resignation at the fact that they would remain there, yet many continued to watch with interest as their madness had grown to the point of revering the rider as god in her own right. Pestilence bent her knees and brought a hand to the woman's chin, forcing her to look into the rider's yellow-green orbs. It would be difficult to tell for certain, but through the fabric of her veil the rider was smiling with warmth and care for truly the ones who did her work were to be cherished in her own twisted way.
"You are now the White horse. You will answer to 'White' when I call you and you will obey your mistress. Once you have served your time then you will receive judgment and be free from this cursed nothingess. The better you perform the more weight my words will carry to aid you when that time comes."
As she spoke tendrils of rotten orange and brown began to sprout from her hand and travel towards Morgan, the instant they touched her flesh the pair became connected as she would find herself unable to pull away while the coursing disease made its way into her. Feverish heat would flow through her veins as the gnarled and twisted effects would begin to take hold, this was Pestilence's blessing of power and the sealing of their contract to be as rider and horse. The rider's left hand conjured long gloves from thin air, floating closer to Morgan's hands before sliding on without any hope of resistance. The long white gloves were coated in white hair just like a horse's and they covered her flesh up to her elbows. Instead of fingertips they ended in hooves that appeared far too realistic in their design. A matching set of boots was summoned as well, repeating the process for her legs except these went over her knees and covered them with a form of padding to protect them. Once both pair were fitted they began to meld and attach to the flesh until there was no seam and no sign that they were not a true part of her body to begin with.
Pestilence gave an almost orgasmic sigh as the process finished and the woman's insides were filled with her rot and decay, for now there would be no pain and little change from the norm but the power and the threat was there at her whims. The tendrils that had burrowed into her flesh would recede and crumble away and the rider's hand would move away from her chin once more.
"Every good horse needs their tack." At this point Pestilence moved to the kneeling woman's side and conjured a white saddle, lowering down upon her back to a perfect fit as it was made just for her. The woman's gloved hands caressed at Morgan's skin as she fastened the straps and buckles to hold it in place. Once she was satisfied that it was secure then she wasted no time in swinging a leg up and over to settle in to her rightful seat.
From there she produced bit and bridle, leaning forward to slide it over her horse's head and force the bit into her mouth before giving a testing tug on the reins. As Morgan was but human her teeth lacked the typical gap that allowed the bit to settle in properly. While Pestilence would not be remiss in simply forcing the woman to hold it tightly between her teeth, she instead preferred to make the edges of the bit almost melt down and connect with the woman's back teeth. In this fashion she could still close her lips nearly all the way and with enough practice she would be able to speak in albeit garbled tones. Of course the rider could always change this in the future when needed, a means of punishment for disobedient ponies that needed to learn their place.
"Ah we are going to have fun together aren't we White? But wait, I almost forgot the most important part. Every horse needs a tail of course." Pestilence conjured the final aspect of the transformation as she leaned back in the seat, a white buttplug with a matching horsehair tail dangling from the end. She brought the toy up to her mouth under her veil as she licked and sucked on the toy to get it nice and lubed up, not hiding the slurping noises as she clearly got into the action.
"Mmm this is my favorite part White. The moment where you cease to be a soul and become a horse instead. Once I slide this in then nobody will be able to see you as human, instead their gaze will reveal a lustrous white horse just like you watched me ride in upon. Of course I'll still know the truth sweetie, don't you worry about that." With unnatural deftness she spun around in the saddle to face backwards, leaning forward to take a good look at the woman's exposed ass as she lined up the plug to her tight hole. Then with slow and steady pressure she pushed it inside, her unnaturally warm saliva doing its job to ease the stress upon her body as the plug filled her tight pucker.
All around the pair the other watching souls could see the changes wash over Morgan as she became a horse in their eyes. No longer was there a woman bound in gear but a white and beautiful horse, hide as of yet unmarred. Of course that would change in time, but for now she could stay pure and beautiful while her insides slowly corrupted away. Pestilence then spun around again to sit forward in the saddle as she gripped the reins.
"Congratulations White, I'm sure in time you'll make a fine steed. Why don't we start with some walking." She made a loud clicking sound with the corner of her mouth while prodding the back of her leather boot into Morgan's stomach, teaching her the signs that the horse was expected to learn that meant for her to move forward.