The first change Jake chose was to alter his forepaws, adding a few options for dexterity and looseness. His clawed toes began to move and shift, lengthening and wiggling, making it much easier for the dog to type. He nodded, satisfied, and typed faster as he drew up his former master as the target of changes. Most importantly, he couldn't have Mike thinking he was the boss of this house. Opening up mental changes, he drew up a number of detailed extra configurations, leaving Mike's personality unaffected but for a massive boost to his suggestibility to anything spoken by Jake himself. Next came a few physical changes, a little bit of pheromone alteration and some of the triggers for arousal altered to something a little more amusing to the mischievous dog. Finally, he set up a very gradual but permanent transformation in the region of Mike's groin and genitals, then swiped his paw to execute the change with a flourish.
Turning the chair, he looked over at his stupid human roommate, who was moaning and jiggling on his bed as he pleasured himself roughly and quickly. Sighing, he hopped down from the chair and walked over, jumping up onto the bed. Mike paused, panting and looking down at Jake with confusion.
"Er, off the bed, Jake, you know you're not allowed up here..."
Jake shook his head, walking up over Mike's body so that his strong black canine form's warmth flowed down over his former master's bare legs.
"No, I think I am, now. After all, I'm not your pet anymore, I'm a proper person, aren't I boy? I think you should take this collar off me, in fact. This is a collar for pets, and I am not your pet."
Mike was a little confused, but as he inhaled the scent of his big dog, he found that he was detecting it much more easily than he used to. The smell of masculine canine seemed to be filling the room, and he whimpered a little, his own dog dick twitching and drooling slightly as he found himself breathing harder and faster, intensely and bizarrely aroused. He nodded, reaching down and unfastening Jake's collar, freeing the dog's muscular neck.
"Good, good, Mike. You seem to be enjoying having dog genitals a lot, don't you? Don't you think it would be even hotter to put on that collar, like a real dog? Enhance the fantasy..."
Mike nodded slowly, everything his dog – no, not his dog. Everything Jake said, it seemed very sensible and smart. He raised the black spiked collar, closing it around his own neck and fastening it tight. Fuck, he felt so hot, being a dog, being horny and dumb. His cock was rock hard, but weirdly, it seemed to be shrinking a little, getting smaller but no less hard. His balls seemed tight and uncomfortable, pulling firmly against his legs and squeezing tight. Jake moved down, lowering his big blunt muzzle to Mike's cock and sliding out his tongue to lick and lap at it slowly, nuzzling and pleasuring the shaft. Mike whimpered and moaned, panting more as his leg vibrated against the bed, feeling weird and ashamed, but unable to refuse or push away the dog. Jake licked more firmly as the cock shrank down at his touch, Mike's balls finally shrinking up inside him, pulling in deep and changing, altering his insides as they altered and spread out, becoming a womb. Soon, the dog was licking a flat space between Mike's legs, which slowly started to grow warm and wet from within, a crevice appearing like a small crease. It grew deeper, the edges puffing out into sensitive lips as Mike moaned with a loud eruption of pleasure. His changing genitals deepened, a wet and sensitive tunnel forming between his legs, which soon pulsed with intense pleasure as Jake's tongue slid up inside it, stroking and teasing him.
Mike's eyes were half-lidded, grinning with orgasmic bliss as his new pussy was licked out by the dominant canine, before he looked down, seeing what was unmistakably a vagina that was being pleasured by his former pet. He suddenly sat up, anxious and terrified.
"Jake! Wh-what the fuck?!"
Jake pulled his tongue free, leaving Mike's pussy wet and dripping as he jumped forward, pressing the human's shoulders back down onto the bed and snarling at him. The smell of dog breath made Mike immediately go quiet, and the feeling of the dog pressing down on him made his new genitals drip with a terrible desire to be filled.
"Shut up, bitch. You want me, don't try to deny it. You want me to fill that bitch pussy of yours with my fat dog cock and you'd do anything to get it. I'm your master now, and you'll do anything I say just to get the feeling of my knot mounting your bitch parts."
Mike tried to argue, but whimpered as he knew it was true. Jake was the master, Jake was so damn sexy and smart that he was just a willing pet. He felt like he would die if he didn't get his master's cock, and get it right now. Jake grinned, seeing his former owner break before him, now his eager and willing bitch, even if he hated what he had become.