"So, what's next?" asked Dan.
"Well, this time I have to do a full cow transformation of ourselves," said Kat, reading off a piece of parchment. "I'm not sure you're gonna like it."
Dan definitely didn't like it.
"What?!" he exclaimed. "Being humiliated like this is bad enough, now I have to do it while being an animal?"
"Look, it's only going to take one day." Said Kat
"ONE DAY?" yelled Dan furiously.
"Would you just listen for once? Jeez!" replied Kat. "If you do this one thing, I promise to never bother you again, even if you're my dumb younger brother. I really need this, I'll even owe you a favor!"
Dan had never heard Kat sound this desperate in years. He thought about it for a long moment.
Finally, Dan replied. "Ugh, fine! But you better magic me up something good when we're done!"
"Great!" She said. "Let's get started."
She casts a teleporting spell, sending them to a nearby farm. They snuck behind the farmworkers and ended up in the fields where the rest of the cows were.
"Alright, we're just about ready, so I'm going to tell you a few things before we transform." Said Kat, removing some of her clothes as she spoke.
"Why do you have to do that?" Asked Dan as he shielded his eyes from his sister.
"I just like this shirt, now hurry up and listen!" Kat said. "When I turn into a full cow, you may not like it, but you're going to have to be forced into my womb and transform there."
Dan shuddered. 'I should not have agreed to this' he thought.
But it was too late now. Too far to turn back.
"Why does everything we have to do either disturbing or disgusting?" Asked Dan
"Because I know you hate these kinds of things." Said Kat, grinning.
"Kat, can we just get this over with? I really just want to go home." Dan sad.
"Ok, fine!" replied Kat.
She put her shirt on a fencepost and faced Dan.
"You ready?" She asked.
"Ready as I'll ever be." Dan said meekly.
"Aight then, here I go." she said.
Kat casted the spell, which immediately made her fall to the floor.
Her horns grew back, as well as her udder and hooves and tail. She grew bigger and bulkier, as her udder swelled and swelled. Her thighs grew in size as her snout grew longer and longer until it became her muzzle. Her tail grew longer as well, and tiny hairs grew on it's tip. Fur sprouted everywhere on her body except for her udder. Her transformation was done.
Kat slayed down on the grass, bracing for what was to come.
Next was Dan's turn. Kat moaned as a long string of flesh escaped from her enlarged bovine pussy and attached to Dan's belly-button. Dan was freaking out.
"What the fuck!?" he shouted.
He realized that his clothes were starting get bigger. He was confused at first, but then he realized that he was getting smaller. But even that didn't make sense since the thing attached to his stomach was pulling him towards his sister's vagina and into her womb.
Kat looked behind her, trying to hide the fact that this was quite pleasurable, and saw that Dan was slowly being pulled into her pussy.
As Dan shrunk even more, Kat's vagina started to grow wider, causing her to moo in pleasure.
Dan couldn't believe what was happening as his feet slowly entered her throbbing, wet, slimy vagina.
Kat could only moo in both pain and pleasure as Dan slid up her vulva and through her birth canal, until finally he reached her womb.
Kat could feel Dan changing in there, his body morphing into the calf she would soon give birth to.
She shivered as her udder built up in pressure, being squeezed against the grass and her legs, her teats getting erect.
After about 5 minutes, Kat felt something burst inside her. Shortly after, liquid escaped her vagina intensely and now had an urge to push.