"Are you sure you're okay with this, son?"
"Definitely, as long as it is what you want, dad"
"You will lose a big part of your intelligence you know, and go through some drastic changes, you might even lose your ability to talk"
"That's fine dad, as long as we're together and as long as I can cum into your big feet every day."
"Speaking of, what if I also became part-monkey? While you turn into a full-monkey, I could be only 50% monkey, so I can still work from home and make money for us, and take care of you"
"I think that's perfect, what about mom though?"
"It'll be fine. She's on a business trip for a few weeks, and we've already been fighting for a while, ending things with her wouldn't be so sudden. And then I could focus all my attention on you, my little monkey.."
Jeff's dad starts rubbing his big calloused veiny feet over his son's monkey dick, making him erect.
"Alright, no point in wasting more time", says Jeff as he grabs the chronivac and selects the new changes. He's going to be 100% monkey, and he's dad is going to be 50% monkey. Jeff also adds a fun little bonus, enlarging his dad's feet way above what a monkey or gorilla would normally have, to somewhere around size 18"
Jeff presses the final button and looks down at his body. It immediately becomes fully covered in hair, even more than before, his whole chest and back are now covered in thick fur, so are his arms, legs and tops of his feet. His feet also grew slightly larger and more calloused and meaty. His dick, to his surprise, started shrinking, becoming about 1-2 inches while hard, the sight really pained him and he wanted to scream "stop!" but no words came out, just this high-pitched sad "oooh, ahh, ahh" monkey sound. He couldn't talk anymore. He also started forgetting some basic stuff, like how to use a toilet or how to use utensils. His legs were also now shorter, and had this stumpy physique. But he didn't hate the new changes at all, in fact, they were making him so hard. He was becoming an animal, a new species, he was no longer human, he now had a tiny dick and huge hand-like feet and stumpy legs. It was a dream come true.
He looks over at his dad who was sitting next to him. His head was now one of a monkey, he was also covered in hair, but looked slightly more human. His feet, as expected, had enlarged, they were probably twice as large as Jeff's head, and they were covered in thick fur. The soles were also a blend between human soles and hands, with meaty pink-gray and rough skin. He already had the hair and smell of a monkey before, but now he was a full-on bigfoot. "This is amazing, son" he said, reaching his big hairy feet towards his son's 1 inch cock. The size difference was insane, his cock wasn't even as big as one of his dad's toes, but it felt great, as if he had his dick deep inside a hole while being cupped by his dad's gigantic feet.
Jeff wants to cum on his gorilla dad's feet, but before, a tail finally pops up from in-between his legs, immediately rubbing itself on his dad's soles. The sensations he got from his tail were intense. It was like rubbing his cock over something, he never thought a monkey could have such a sensitive tail. He stands up, lifts his bigfoot dad's foot towards his erect 1 inch cock, and start intensely pushing into it and rubbing up and down along his sole, all while licking and chewing on his other meaty foot, getting the large strains of hair in-between his toes wet. He finally came and it was the best orgasms of his life. He knew right then that that's how he wanted to stay, As a care-free stupid monkey dedicated to fucking and worshipping his hybrid dad's furry feet.
The next day Jeff woke up. Just his primal instincts remained, and he was hungry. He made his way to the kitchen, walking on all fours. His dad was up cooking something. Jeff crawled on the floor and started sucking and playing with his toes. Eventually he got too excited and pushed his microscopic dick under one of his dad's big toes. He felt the sweat and roughness of the half-gorilla's soles, cumming immediately and making more high-pitched monkey sounds.
"Ha, someone is having fun" his dad says. "Breakfast is ready, you can sit down". Jeff was only understanding part of what his dad was saying, but he saw he brought a plate to the table, so he moved there as well. He jumped on top of the table and laid there with his huge monkey feet towards his dad. His dad got erect as soon as he saw the beautiful grey soles in front of him. He plopped his huge, thick, bigfoot legs on the table reaching his meaty soles all the way to his son's cock.
"We should really eat first Jeff" he says and he starts rubbing his giant stinking feet on the plate of food, bringing them to his son's head. Jeff enthusiastically licks up all the food from the warm soles, and pushes them back down, cupping them around his dick and pumping up and down. Meanwhile, his monkey feet reach down to his dad's erect cock and start pumping it as well, with even more hand-like dexterity. They achieved the peak of feet sexual satisfaction, giving each other footjobs that had all the stink, sweat, and size and hair of a foot, but with the precision and dexterity of a hand.
That night when his dad came to bed, Jeff crawled to the bottom part, aligning himself horizontally so that the dad's bigfoot feet cover both his dick as well as most of his stomach, he felt warm and safe as he reached climax after climax all night. feeling and tasting every part of his dad's rough meaty feet, rubbing every hair and absorbing all the sweat into his fur. When his dad's feet started wiggling, he knew it was time to move his gorilla feet up to the bigfoot's thick penis and pump until he feels the warm cum flowing between his monkey toes. It was truly paradise, spending his every day resting and fucking his dad's feet, hundreds of orgasms each hour, he couldn't wish for anything more.