The road is completely empty. As you two get closer and closer to the cottage, you feel hotter and hotter. You begin sweating and move your back and butt uncomfortably. Jack is quiet, but he is gazing at you passionately. He purrs like a kitten when you scratch behind his ear.
"OK, Jack, we are here!" You open the door on your side and step on the ground. Your body still feels strange. Your clothes feel real tight on your sweating body. But your lust takes you over completely. You rush to the big barn by the cottage and open the door. That's when you finally notice what is going on to you.
RIIIIP! You hear a big sound from your back and feel cool night breeze on your butt. Your butt starts growing! You open your mouth trying to scream in horror, but all you can do is pant and moan.
Jack opens the back doors of the van with his strong hinder legs and walks up to you. "Get in" says he in a deep and husky voice and grins at you. His orangish brown eyes glisten in the moonlight.
You hold your growing ass tightly with your hands trying to stop the change, but it keeps sticking out further and further, rounder and rounder, fatter and fatter. The white soft fat is spilling between your fingers. Your tight boxers slide down to the middle of your butt and are quickly showing the rest.
Jack pushes you in your fattening ass with his muzzle, and you trip into the barn, into the darkness you never knew. You are helpless, fearing and feeling so tired, no energy to move. Jack's immense body blocks the moonlight behind the door. "You know what I want." Jack closes the door with his paws. "But I can't take it - yet." Steps toward you. "It's not ripe yet." Rolls you over on your belly.
Your butt becomes twice as big as before. Although you fear what is going to happen next, your member grows hard and your anus twitches in lust. You feel Jack's heavy furry body on your back and his huge cock placed between your ass cheeks. He starts moving slowly, then picks up the pace.
Your butt crack gets filled with a copious amount of Jack's precum and your sweat. His moan gets louder, and his cock grows thicker and longer. All of the sudden, he removes his member from your ass crack and shoves the tip into your asshole. With a big roar, Jack dumps cum into your small human asshole.
"AHHHHHHH!" His cum is burning hot inside you. Your belly quickly swells up with the huge amount of his cum. You then feel your body starts absorbing it! The bottom of your belly slips out from your T-shirt, the seams of jeans on your thighs burst open, your chin grows quickly to a double chin. But the biggest change is your ass - it grows out of your jeans completely and fattens like a balloon. You then reach the climax too. All the fat you are putting on is making you extremely horny for some reason.
"Fuck yeah..." Jack laughs in a hissing voice, looking at your growing body. "Soon, dude, soon..." He licks your growing ass and places his hard dick between your fat cheeks again.
The fattening session continues. Jack shoots gallons of cum into your ass over and over, and you have gained well over 100 pounds in fat. You are completely lost in sensation and give in. All you want is his huge fat cock inside you, and you would be glad to give up anything, even your mobility, for the real ass fuck.
Jack stands up with four legs and steps away from you. He stares at your new fat body and your big ass with lust. "What do you want?" says he. "F... fuck me..." "Where?" "In the ass..." "With what?" "...Fuck me in my fat ass with your huge cock!" Jack grins. "Gladly."
He sticks his muzzle into your butt and licks your wide open asshole playfully. Electricity runs through your body. "Ahhh! Fuck me!" Jack finally mounts you and places his raging member to your waiting asshole. You feel your well-lubricated asshole is widened and his cockhead slides in you. His cock soon touches your prostate and your rock hard cock jumps up.
Jack doesn't stop there. He pushes his 14-inch cock into you to the base and starts pounding real hard. His fat belly and chest on your back, his thick fur, the smell of his sweat and musk, his hot breath, his moan, and his huge member constantly rubbing your prostate - you are in heaven.
With a big roar in the primal pleasure, he finally shoots thick cum inside you. "Fuuuuuuuck!" You shoot the load as well. Jack humps vigorously for another minute or two to unload.
Your body starts changing again. But this time, the change is more drastic. You feel your face begins sticking out into a muzzle, your hands and feet are getting stiffening into paws, a bushy tail is growing just above your fat ass and from there thick fur is spreading to the whole body, your cum is becoming so thick that you can even feel it moving up in your cock from your fist-size balls, your twitching member is growing longer and fatter, and your entire body is bulking up with muscle and fat, getting taller and taller.
You are becoming a bear.
"Welcome to my world." says Jack, panting and grinning, and starts pounding your ass again.