Red was rubbing his penis against one of Cow's teats. Milk was dripping from it, flowing down the front of his shaft and making his balls wet.

"But before i use my... rod on you, i wish to lighten the load in your... magnificent mammaries." Red said.

He kneeled down, enveloped her upper-left teat with his mouth and started drinking the high-pressure milk coming out of it. With his left hand he alternated between pinching her upper-right teat and groping her udder in that general area.  Cow was deeply aroused by this. She started squeezing one of her lower teats with her left hand. She was feeling a pleasurable sensation in her pussy and started rubbing her pussy up and down with her other hand. Red noticed this and gave a soft, perverted chuckle while sucking on her teat. He also gave her a wink. Red was drinking a massive amount of milk infused with growth serum. His belly started to enlarge. His arms and legs were also getting thicker. He was getting fatter. But he barely noticed anything except except the wonderful sensation of his stomach filling with delicious, warm milk.

Cow kept milking herself and masturbating. Red's growing abdomen and genitals were being coated with milk. She was feeling a sensation building up between her legs. She has only masturbated once before, which felt nowhere near as good as what she was feeling now. Very soon, all the stimulation her pussy and udder received caused her to have a very intense orgasm. Her vaginal discharge burst from her in several, short, intense squirts and splashed on the floor underneath her, also getting her udders wet as well as Red Guy's balls.

"Dyooooooaaaaaaah! Ah! Ah! Ooooooooooh...Moooooooooo..." Cow screamed and moaned loudly in pleasure.

Red stopped groping and drinking from her udders when Cow orgasmed. After a few seconds, he stood up, his new fat body giving him some trouble in that endeavor.

"Oooh my! You reeeealy enjoyed that, haven't you, my bountiful nymph? I'm glad i could help a girl get her... happy ending. Or should i say... future woman. And i may have been carried away when drinking. Can you blame me? But i quite like my new look." He said seductively.

Red Guy was lightly stroking his cock and carressing his newly fattened body at the same time. Cow was liyng on her back, panting heavily. There was a large puddle of clear vaginal discharge fluid and milk starting from between her legs and going farther down, also pooling around Red's feet. Her udder had shrunk in size quite a lot, but was still almost twice as large as it normally was. Red knelt down in front of her pussy and pushed his large ball-sack behind him in order to position his cock right in front of Cow's vulva.

"Now i'm going to... well, put my cock inside your naughty pussy. I'm going to try to open those floodgates of yours again. Mine will certainly open. N-huh-hum! Let me do the work, my bovine beauty. You just sit back and... enjoy." he told her.

He started rubbing his glans on her labia and clitoris, which made Cow slightly shiver in delight. He then slowly inserted his penis inside her untill its full length was inside her vagina. Its wetness helped greatly. There was a small bit of pain as her hymen was breaking from this action, but was quickly replaced by pleasure as she could feel the contour of his twitching cock inside her tight, no-longer-virgin pussy. Red started thrusting slowly. He then started picking up speed. His breathing was getting heavier as he talked dirty to her, telling her about how much he used fantasized about her. Cow, on the other hand, made pleasure-tinted "moo" sounds as well as the ocasional "yes" and "oh". She was also stimulating her udder. As he was fucking her, he asked her to put a finger in his ass. After assuring her it was clean, she timidly did. One finger became two, then three, eventually leading to  her fisting his ass as well as groping and slapping his buttocks.

Red Guy was now picking up speed. His cock was now leaking a small stream of precum at a constant rate. Cow's breathing became heavier and heavier as Red Guy started pounding faster and deeper while holding on to legs. It did not take long for her to climax again, splashing her vaginal discharge onto the lower half of Red's enlarged, jiggling belly as well as his legs and big, swinging balls. Her orgasm quickened his own, and after about a dozen seconds, he came too. His semen immediately filled her pussy and the excess rushed out of it, splashing around his balls. As he came, his thrusts became short and twitchy and helped his cum almost completely cover the front of the lower half of his body as well as Cow's. Cow started growing from his cum. Her belly inflated rapidly at first, growing to a very large size before its mass spread to all the rest of the body, making her quite obese.

"Oh! Oh-ho-ho! Oooh myyyyyy! Oh, my goodness! That was amazing! I never shot my load as intense as this. Oh... I really needed that. I wanted to fuck you for sooooo long, my dear Cow." he said in ecstasy.

They both stood still for a while, enjoying the wonderful afterglow. After about a minute, Red took his now flaccid cock out of her pussy and lied down next to her. He started hugging her and kissing her cheek. She started kissing him on the mouth. They loved pressing their newly-fattened bodies together They both shared some tender kisses and caresses for a while and eventually french kisses too. Red then got up and walked in front of her. His large, round, fat ass was facing her.

"Now... i just want one more thing from you. The... pièce de résistance. This is gonna be a bit weird. Well, weirder. Right, so i'm bigger now. All of me is. And i've been anally pleasing myself quite often and with some big toys. So this might just..." Red was thinking aloud but was cut off by Cow.

"What is it, Mister Red?" she said.

"Hmmm... guess i should get straight to the point. I... I want you put your udders in my butt." he said.

Cow said nothing at first.

"And fill it up." he continued.

"Ummm... will my udders... fit in your butt?" she asked.

"I do believe so. I often like to give my derrière quite a work-out. Besides, your udders are smaller now. And my hiney is bigger. Plus, you have plenty of lubrication. Be a dear and squirt some milk on my butt before we proceed, will you?" he said

She milked herself, making his massive butt-cheeks wet. She squirted the most amount of it between his cheeks. He then spread his buttocks, and then inserted two fingers from each hand into his ass and spread his anus open. He then inserted the remaining two fingers from each hand and gaped himself open very wide. The gaping hole was almost wide enough to fit Cow's entire udder. Fortunately, her udder was soft and malleable. She was looking at the gape and could see some of the pinkness inside of his colon.

"I have experience with these things. Now, quickly. Put it in." he said.

She timidly waddled closer to his open anus. She grabbed her teats and brought them together using her fingers, which caused them to squirt some milk into the hole. She pushed her udder in his anus. It was slightly bigger than the opening, but once it started going in, it was very easy to squeeze it inside. It took slightly over one second for her udder to be inserted completely into Red Guy's awaiting ass. He then stopped holding it open with his hands and it closed slightly, squeezing Cow's udder and sending milk squritng from it into his ass. He involuntarily clenched his ass around her udder, sending an even greater volume of milk into him. He loved this new sensation. Nothing had ever filled him up with liquid like this, wether it was a cock or a toy. He started masturbating, but very soon could not reach past his expanding belly. He could not finish his climax without help. Cow loved it as well. She was masturbating and groping his massive buttocks as Red's ass was clenching and draining her of milk. It eventually caused her to climax once more. Each ass-cheek of Red was now more than twice as big as her udder normally was and it continued expanding as her fattening milk filled him. Red was getting fatter than ever. His belly had grown massive, almost bigger than the rest of him. His arms and face weren't getting big enough to keep up with the rest of him and had the appearance of "sinking" into the rest of him. He had grown multiple fat "chins" and the cheeks on his face were big and round.

Cow's udder was finally almost completely drained. She slipped it out of her ass. It looked somewhat deflated. A large amount of milk escaped from Red's ass, but it was minuscule compared to the amount that remained inside him to transform him into the huge blob he now was.

Red asked her to help him cum once more. She obliged, and masturbated him. While doing this, she told him she would be returning to him soon for further negotiations. The two discovered that with some orgasm denial and by draining themselves of milk and cum, they could lose most of the weight they had acumulated. They both did this for a while. Later that day, Cow left Red's house feeling happier than she had ever felt in a long time.