You weren't sure about this at first, but you placed the order, and now it arrived, and you held it in your hand. A simple black collar with a silver name tag with your name on it. You placed the order online, claiming it was for a large dog, but in truth you got it for yourself. You also got a few sex toys, including an onahole and a dildo. You weren't sure about using the dildo, but it came free with the onahole. The shipment was a pain too, but the onahole was that of a dog shape, and you couldn't wait to have a night of fun.
 
Just as you pulled down your pants, eager to play with the toy, you swore you heard a small whisper from the collar. You glanced at the collar and tilted your head. "Was the collar always dark purple?"
 
You swore you got a black leather collar, yet now as you look at it, the collar looked purplish. There were also small silver studs that lined up the outside of it. "Huh..." With a shrug, you casually slipped it on first. You knew your fantasies were odd but living them out in private was surely not a big deal.
 
'Oh, this feels SO nice. I could wear this forever.' You heard in your mind. You figured it was your own thoughts playing tricks on you, as the voice appeared randomly, and sounded very feminine. You ignored it for now and decided to have some fun.
 
Just as you pulled out the onahole, you felt a growing erection. You swore you felt a poking sensation on your rear, which was enough to make you jump. You quickly turned around and saw the dildo positioned behind you! Specifically, the dildo looked as if it wanted to penetrate your ass.
 
"Yeah, I'm not ready for that part." You pushed the dildo aside and began to sit down again. Just as your rear touched the seat, you felt the dildo on you again. You know you moved it! Frustratingly, you reached behind you, grabbed the dildo, and tossed it to the other side of the room before you pushed the tip of your cock into the onahole. "There. Now let's see you get over here." You said, teasing the dildo.
 
'You moved it though. You know you want that dildo in your ass and cunt.'
 
You heard the voice again and glanced around. Now, the voice was starting to get a little creepy. You almost wanted to call out to the voice, but you felt silly for even thinking such a thing. Then again, you were already trying to fuck an onahole entirely naked except for a dog collar. Things were already looking a little strange. You fell back in your bed in wonder. "Is that voice really me?"
 
'The voice is of your mistress. Every hellhound needs a mistress.' A voice replied.
 
A hellhound? You looked down at your body. You were quite sure you weren't transforming, though the fantasy had crossed your thoughts more than once.
 
'Oh, I can tell you don't believe it, but you need to see it. Why don't we start with that signature spaded tail?' The voice continued.
 
You glanced back with curiosity. If your mind was really messing with you, then it wouldn't change anything. You felt a tingling at the bottom of your spine, but that could be anything. Just then, you felt a strong throbbing in front of you. You gasped as your cock let loose a small spurt of cum, but not enough that one might release in an orgasm.
 
You felt a short tail grow behind you as you orgasmed. With every spurt of your cum, your tail grew just a bit longer, and you watched it grow outward. The base of the tail was dark and furry, but as the tip appeared, it looked much more pinkish in color with a spaded tip. While the tail was only a foot long, you couldn't resist touching it curiously. It was odd to feel the tail touch from 'both' ends, and the tail coiled back in response. "Ack! How did... but this is..." You couldn't believe it. Your shaft was still rock solid, and you had a tail!
 
'Do you believe me now?' The voice said. 'I am your mistress, and you are my hellhound. You will obey me and worship me.' It spoke in a sultry seductive voice, though with a tone of dominance.
 
There was no question, the tail was real. The dark colored fur on it spread to your ass slightly, and even plumped your rear. You stroked your ass, and it made your cock shiver in anticipation, as if it were ready to orgasm again. "Yeah... why... why does it feel as if I can cum again?" You ask in a frightened tone. Your fingers shivered as you stroked your tail. It felt as sensitive as your shaft.
 
'Demonic energy of course. A succubus must be able to orgasm dozens of times, it would only make sense for the hellhound to cum many times as well. With every orgasm, you permanently lose more of your humanity, unable to return. Although would you want to return? I can make you feel so good.' The dildo that you threw vanished. It reappeared directly behind you and brushed up against your back, above your furry ass cheeks.
 
You quickly hopped up and turned around. You swore that, for a moment, you saw a red creature with black hair attached to that dildo, but as soon as you swore you saw it, it vanished. "I'm not a hellhound or anyone's pet or anything like that." You crossed your arms with an angry look. You weren't sure how this happened, but you were going to get rid of these sex toys if they had a demon possessing them! The part about demonic possessions wasn't on the website!
 
'You put on the collar. The moment you put on that collar, you agreed to be my pet. Mph. You can feel it, can't you? The power flowing through your body. You love it, don't you?'
 
Just as the voice said that you felt a growing heat pulsate through you. With every beat of your heart, the heat intensified. It felt as if your veins were on fire, though there were no pains to accompany this sensation. With this heat came something else. You felt power flow through your veins, a power unlike anything you've felt before. You weren't sure what you could do with it, or what kind of power it was, but it felt good.
"No... No, I don't like it." You said, though it was a lie that was hard to speak.
 
'You're a poor liar. Hellhounds should be much better at lying.' The voice mentally laughed. 'Now, let's give you more changes. Cum for me. You know you want to. You need to.'
 
"Uggghnnn." The voice was too much for you to bear. You grabbed your shirt and tore it open as your shaft orgasmed. Your cock poked up and came onto your crotch. With every wave of your seed, your nails sharpened and took on a pinker sheen, both fingernails and toenails. Three additional sets of nipples began to appear down your chest and run down your front, though very faint in appearance, every throb of your shaft caused them to appear just a bit more. Your ears became sharply tipped, and your nose turned as pink as your nails. Your orgasm lasted twice the length of any normal orgasm you ever had, and once finished, you laid back and panted heavily.
 
'There we are. Too much cum lost to change back. Don't you feel much better? I can form myself much better here too. You're losing more than just your humanity with those orgasms.' The female voice said. Her voice sounded louder, as if she were directly behind you.
 
You turned around with wide eyes to find nothing but the dildo, but the dildo floated in the air as if it had a life of its own, and right in the area where one might have a sex. It moved forward in front of you and gave a playful wiggle.
 
'Ah. You can't tell, but this is my cock now. Technically. Doesn't it look good? You'd love to suck it like a faithful hellhound, wouldn't you?'
 
You stared blankly at the cock, half in disbelief, and half because you wanted to suck it, if only to know what it felt and tasted like in your mouth. Saliva dripped from your open jaws. 'Um... help... someone?' You thought, but you were alone. Even if someone could find you, you were already beyond human. You felt two small horns atop your head, but you couldn't reach up to touch them with your hand. It was as if your hands had to face downward in front of you, and it took a lot of effort to reach. Worse yet, you were still hard. Cum soaked your shaft, but ready for another round of orgasm to cum again and lose more of your humanity.
 
'Oh, but we're SO far away from your finished transformation. We must take our time and enjoy your corruption, your slow conversion into my pet. You'd like to see what your new home would be like? Or maybe you want me to take over your house and change it to my liking.'
 
You wanted to say no, but you opened your mouth and let out a deep growl instead. You felt your new sharper teeth grind against each other as you looked at the dildo with rage. You felt ready to bite that cock and pull it away from whatever it was on.
 
'Now, is that any way to treat your mistress? As I said, you're already mine. You can't hurt me. Any attempt to harm any part of me, including my cock, will only result you in pleasuring me. Since I just gave you that command, you MUST obey it, whether you want to or not.'
 
As if wanting to prove your mistress wrong, you lunged forward at the cock with your small fangs bared. You raced up to the invisible figure, moved your mouth over to the floating cock, and promptly sealed your lips around the shaft and felt the toy with your tongue. The floating dildo tasted like rubber, though you felt a pulsing sensation behind it. 'No! What are you doing? Stop this!' You shouted to yourself, but you knew it was unlikely to prove successful as you sucked and licked away at the cock.
 
'Ah. You love this, don't you? You're so close to orgasm. You must bring me to orgasm, and then you'll cum too. You look forward to it. You want it, you must have it. Pleasuring your mistress brings you more pleasure to yourself than you could ever imagine.'
 
The more mistress spoke, the more her words rang true to you. Your eyes rolled up in bliss. You were so close to orgasm. You had to get her to do it first. You didn't even think about how her cock was mostly that of a toy. She could still orgasm as it... right? The only way to find out was to keep sucking.
 
It didn't take long for you to suddenly get the taste of precum in your mouth. The moment you tasted that hot seed, you felt your own shaft orgasm. You closed your eyes and let out a muffled moan as you came. With every pulse of your cock, your tail twitched and jutted out a bit more than the previous twitch. You felt dark fur slowly grow out parts of your body and warming you up, making you feel even hotter than before. You could feel your human mind slowly melting away from the heat like a lit candle. You felt more fur grow out of your arms and legs, red fur that made you feel even hotter, and all the sexier. Black spots appeared on your fingers and palm and began to expand.
 
You pulled back and glanced up. You could barely make out a blood red colored demon, though she was faint, as if a ghost appeared in front of you.
 
"Ah, a little more real, a little less ethereal." The demonic woman spoke. Her voice was faint, but there was no question that it was real and not in your head anymore. She put her hand through her body with emotionless eyes. "And you can go right through me. Well, except for my cock." She chuckled. "Perhaps you'd like to get back to sucking it?"
 
You pulled back from her. You looked up at her tentatively. Part of your mind really did want to get back to sucking it or stuffing that cock into your ass. You tried hard to fight these instincts, but even your grown tail taunted you as if it had a mind of its own. The tip of your tail looked spaded, but a four-dimensional spade, a bulb ready to burst. The tail tilted down and taunted your shaft as well as a small spot around your testicles. The tip of that spade almost felt as if it were penetrating your body.
 
"You like that feeling, don't you? A cunt would suit you so much better than a cock, wouldn't you agree?"
 
You spiritually shook your head no, but you felt your body physically shake your head yes. You loathed the idea of having a vagina, yet at the same time the cock felt so wrong on your body. You couldn't see it, but your shaft was already smaller, as if it wanted to give in and transform into a vagina already. You gritted your teeth and looked away as if you were in pain, when in truth the pleasure was growing immensely, all while your human mind continued to melt away into nothing.
 
"Why don't we transform it then? Roll onto your back." The demon chuckled. "Roll over girl." She teased.
 
Your body stiffened as you heard the order. You wanted to resist, but as hard as you tried, you found yourself kneeling and rolling. You stopped on your back with your arms and legs in the air, both of which had changed in length to better suit a four-legged form. Your cock bobbed out in the open, tilted enough to point to one of your several nipples. Your shaft felt more like a canine's own, but you know it was the least changed of your entire body, as if your body knew it was going to inevitably lose your manhood anyway.
 
"That's a good girl. Who's a good girl?" The demon got down on her knees and rubbed your stomach, at least it tried to. The form was still mostly ethereal, which made it difficult to touch solid matter.
 
You could feel the demon against you, and when its arm went underneath your fur and skin, it sent a wave of lust unlike any other. You let out an inhuman whine of joy. Your tongue lolled out of your mouth as you smiled down at her. Mentally, you screamed to stop, but you had to obey her. She was your mistress, after all, and no matter how hard you tried to think otherwise, the thought always came back. She was stronger than you were.
 
"That's right. Now, good girls don't have cocks, isn't that, right?" The demon taunted. Her hand lowered down to your crotch and stroked it softly. "So, you want to cum and lose that manhood, don't you girl?"
 
You felt your body nod once more. You whined in delight while pressure filled your cock. Yes, you had to orgasm. You had to cum and get rid of that cock of yours for good. You needed a little more. Part of you wanted to lean down and see if you could suck yourself off like an animal, but you refrained. You were in front of your mistress after all. You also still had the skeletal structure of a human, at least mostly. You had more flexibility. You weren't sure how you knew; it was as if it were instincts. It just wasn’t quite enough.

“Now, why don’t we make you lose your manhood in a very special way?” The demon’s hands tickled your tail delicately. “A spaded bulging tail is nice, but we can do better.”

It was hard for you to focus as you were so close to orgasm. Your tail, long enough to move to the front of you, slowly parted at the tip and revealed a cunt on the inside. You could feel a rush of air to your cunt, and it made you nearly want to cum, but you couldn’t! You thrust your hips forward, as if attempting to encourage yourself to orgasm, but nothing came out of your cock. Your new cunt at the tail meanwhile, was dripping wet with ecstasy. Your new tail cunt plunged down onto your cock.

“Hah! Watch as you fuck yourself. It feels amazing, doesn’t it?” The demon teased. “Cum, cum for me and become a woman. Orgasm in your new tail cunt and show me how much you love it.”

With a yelp, you orgasmed once more, and in your new tail cunt no less. You couldn't believe you were cumming so much in such short periods, and with every pulse and throb of your cock, your shaft shrank while your testicles pulled back. You reached down and gently grabbed the tail. You stuck out your tongue with your face beet red, and a look of ahegao while your fingers toyed with your shrinking testicles. Your cock let out one more spurt as it shrank to the size of a clit, and an opening appeared behind it as the cunt. Your tail pulled back and let you see your new feminine cunt and you let out a moan. "Ahnnnooohhh fuck!" You let out a noise both canine, and human.
 
"Heh, good girl. Now truly a woman with a wonderful cunt. Now, let's work on those tits of yours. You have many nipples, but your chest is still so flat. That will not do for a woman like yourself." The demon spoke. It was a bit harder to see through her as her translucent body became denser, though she could still penetrate solid mass if she so desired.
 
You looked down at your chest, covered in a dusting of red fur. You stroked it and felt a large increase in sensitivity. "My...chest?" You said as you slowly recovered from your many orgasms, but you felt a new heat between your legs that felt alien, yet also incredibly good. "I'm not... I'm not your... hellhound. I'm not a... female hellhound."
 
"Your lips say no, but your mind says yes. Even your very soul is converting into it." The demon's eyes briefly flickered of pure blackness before they turned to a shade of red. "You should consider yourself lucky. It will be much easier to achieve orgasms with a female body. Just a little fucking of yourself with that tail and you'll soon have the shape any woman would kill to have."
 
You pulled yourself up and panted heavily. You didn't feel sweaty, but you felt so hot, and it was as if you could only sweat through your mouth, as if you were a canine. "Yeah...well...f-fuck..." You almost went down to your knees as your tail teased your cunt. "Uhhnnn." You tried your best to control your tail, but it went against your emotions. Rather, it went with your feelings of desire that you attempted your hardest to hold back.
 
The demon grinned. Her fangs looked as sharp as yours. "Fuck me? You don't have a cock anymore. This cock though..." She slapped her cock, and it was as if rubber slipped off her shaft to reveal a beet red shaft that almost looked like a canine's own, complete with the red bulbous knot at the base. "It can fuck you until you're full of hellhound pups if that's what you're looking for."
 
You couldn't believe what you saw. Her cock, the only part of her that was truly real, became an actual cock with a simple slap. Mistress was truly more powerful than you could imagine. You thought about that cock fucking your cunt, and your tail couldn't help but mimic your thoughts, pretending to be the shaft. Your knees buckled as you let out another orgasm with a stuttering moan. Clear feminine fluids rushed out of your cunt as your chest inflated into C cup tits, and your torso took on the feminine shape of a woman. The tip of your tail closed and did not hesitate to take advantage of your thoughts to keep fucking you as the image of the cock was in your head. You reached up and grabbed the sides of your head, as if to pull the thoughts out, and you paused as you felt not one, but two sets of ears on each side of your head. As you felt the extra ears, it suddenly felt appropriate to have. Extra ears on a hellhound? There was nothing strange about that.
 
"I can see you're beginning to understand what you really are now." The demon chuckled. She reached out and stroked your shoulders. As her body solidified, her touch became real. "Now, why don't you tell me what you are? I want to hear it from your lips." One finger delicately ran across your mouth.
 
You parted your lips and your tongue stuck out slightly, now split in a serpentine look. You gave her finger a few gentle licks instead of the bite down on it, showing her earlier command was still in full effect. "I'm..." You knew what she wanted you to say. You were her pet, her plaything. You were her to command. Your tail stopped thrusting in your cunt, but it teased your thighs playfully. Your new vagina dripped with arousal as you avoided telling her what she wanted to hear. Your tail opened again and brushed your thighs with its exposed cunt, as if to intensify the pleasure.
 
"You want to be a good girl, don't you?" The demon's own tongue, as serpentine as yours, brushed against your furry cheek.

‘Yes…’ You thought to yourself. You had to be a good girl for your mistress. Fur continued to sprout rapidly from your body. You fell back and stroked your cunt with one hand while squeezing your tits with the other. You felt your paw pads, but you could still use your hands to pleasure yourself, which you wasted little time doing. “I’m your hellhound.” You continued to try to resist, but the more your cunts were dripping with arousal, the harder it was to say no.
 
“That’s right. You’re not just any hellhound.” The demon’s cock pulsed. She was as real as you were in that room by now, including that cock that was hard to take your eyes off.

While you could resist by toying with your cunt and tits, your tail cunt couldn’t help itself. The tip of the tail opened and revealed your cunt again before it suddenly thrust down on the demon’s cock. You could feel the cunt fucking the cock, and you let out a sharp gasp and a deep moan that almost sounded like a canine whine of pure pleasure. “Ahhnnnooo!” Your back stiffened as you felt your tail cunt fuck that cock. You wanted to control your tail, but it acted on your instincts and desires, and you desired cock.

The demon simply laughed as your tail cunt fucked her cock. “Oh yes! Give in and become a faithful hellhound. Orgasm for me, finish your transformation!”

You continued to moan and finger your cunt while your tail cunt fucked her cock. It wasn’t your cunt between your legs that orgasmed repeatedly, but your tail cunt as well. With every orgasm, your body changed a bit more. Your hair turned red and took on the look of a mane. Your horns grew in length while another set grew, that new set growing around your ears. Black fur covered most of your head with red fur beneath it and sharp fangs poked out from your mouth. Your hands were still more than usable, but had the resemblance of paws, and shorter fingers, complete with one finger vanishing during the conversion. 
There was a tuft of red fur on your chest, above your tits, and light purple scales scattered around your body. Your curled toes changed into hooves, and your transformation slowed down at the same time your orgasms slowed. Your tail cunt pulled back, satisfied for the time being. With one more small orgasm, your eyes became slitted with pink pupils, and black irises.

“That’s a good girl.” The demon’s cock throbbed eagerly. “But you didn’t let your mistress orgasm in you. You were cumming yourself, and repeatedly. You are a good girl, but you could be better. You need to let your mistress cum in you and finish transforming you.”

“H-huh?” You released your tits and put your paws on the ground. You sat up and glanced at yourself. You were a hellhound. You were an anthro hellhound, but you were still one. Your tail flickered behind you, shedding a small amount of its fluid on your bare furry back. “But… I’m finished, aren’t I?”

The demon shook her head. “Your body is only partially transformed.” She placed a finger on your chest. “And your soul is not. Your soul is still human, and we cannot have that. You must finish your change, and I know the way to do that, as do you.”

You were confused at first, but your instincts told you how to finish changing yourself, how to give in to the corruption. You were already too far gone to turn back, and you wanted to make your mistress happy. Making your mistress happy meant far more pleasure for you too. You rolled onto your stomach and felt your many nipples against the ground. You got onto your knees and paws. Your ass wiggled enticingly towards your mistress. “Please… please fuck me. Please finish changing me.” 

The demon stood behind you and kneeled. “For my faithful hellhound? Gladly.” She thrust her cock into your cunt, your cunt between your legs. Her cock pushed in deep, and she wasted little time getting to work humping and pumping.

You couldn’t believe the amazing sensations. You thought fucking your tail was amazing, and getting your tail fucked by her was bliss on another level, but to feel her cock in your cunt immediately began to bring yourself to orgasm. Your cunt clenched and released her cock repeatedly while your tail wrapped around her, opened, and brushed your second cunt along her body. You couldn’t help but give in, and as you gave in, you began to change even more. With every orgasm, you felt yourself change more. You let out a deep moan, which sounded very feral.

“Mppphhh. Yes.” The demon called out as she thrust deep into your cunt. “Change for me. Become nothing more than a feral beast, lusting for sex, always in heat.” She ran her fingers along your tail and penetrated your tail cunt with those same digits.

You felt your stubby paws merge together as you felt her penetrate your tail cunt. Your tail thrust back and forth with her hand while your hips bucked with her cock. ‘Fuck! So good! Ahn!’ You couldn’t control yourself. With every orgasm, you felt your thoughts turning more primitive. Your body was hot for cock, and the one in you made you feel amazing. Your legs began to shrink, though it made it easier to stand on all fours.

“Yes, keep cumming. Keep orgasming. Turn into my feral hell beast. You crave it, you know it. Body, mind, and soul!”

You raised your head and lolled out your tongue in pleasure. Your orgasms never seemed to end as you kept going. You had to make your mistress cum, you had to satisfy her. You felt as if your body wouldn’t truly finish changing until that happened. You had to bond yourself with her with more than humping her cock.

The demon thrust her cock deep and grabbed onto your tail cunt. With a grin on her face with fangs as big as yours, her canine cock knotted and orgasmed. Her seed pumped and pulsed as it flowed into your newly made cunt. As she came, you could feel yourself twisting and transforming inside in ways you couldn’t imagine, but it gave you a feeling of power like none other.

As you felt her cum, your body finalized its transformation into the feral beast form. It was an alien form, but it felt so right, it was the same form your very mind, and soul bent to accepting. You were a hell beast for your mistress. Your job was to make her happy, and you knew you were doing it with her orgasm. You growled up at her happily and pressed your ass back against her crotch playfully. Your body permanently in heat, and your mind reduced to nothing but a beast, and you couldn’t be happier.

Your mistress stroked your back and gave your soft furry ass a squeeze with her free hand while her other hand continued to toy with your tail cunt. “Perfect. Now you’re ready to begin a new life with nothing but you, me, and your lovely collar.”

