Brian has always felt bad for his younger brother Dave. There wasn't a huge age gap between them, only 2 years, but there was a big size difference. Dave had always kinda been the runt of the family, being only 5'3" at the age of 20 and very skinny. It certainly didn't help that Brian and out dad they were both athletes, working out often and being quite tall, Brian being around 6'4". Brian liked Dave, but would make fun of him quite a bit for his size, just joking around, like any older bother would. The one thing he had to his advantage was his smarts though, having gotten into a prestigious university, making it so that our parents were quite happy with him. Brian decided that he wanted to try and help him a bit for his size, so he went shopping.
It was the summer, Dave was off of college, and Brian was searching for a job, having just finished my college. Brian went into town and looked around for a drug store that he heard about through some online forums. He eventually found it, it was in a secluded alleyway deep in the city, clearly not getting much foot traffic. When he walked in, he was greeted with a pleasant aroma and some light classical music playing. There was a rather large and intimidating man at the counter, and Brian decided to ask him for some help.
"Hi, I was looking for some growth supplements to help my little brother grow" He said as he approached the man.
"Sure thing, what were you specifically looking to grow or change about him?" the man replied, coming off surprisingly calm.
He thought about it for a bit, not having considered it before. "I guess just some height, muscle, and maybe a bit of confidence" he replied, "I'm not really sure what he wants, but an all around improvement is probably whats best" he added.
The man just smiled and walked into the isles of supplements and returned with a bottle of pills, "This should do it" the man replied, flashing what Brian could of sworn to be a smirk. Either way, he thanked him for his help and purchased the pills and returned home. When he got home, he decided to start Dave's help right away. The only thing was, he didn't want Dave growing bigger than me, sure he liked Dave, but he still wanted to be the big brother, in both age and size. Brian didn't bother reading the label of the bottle assuming it worked like any other supplement. He remembered that the man had told him that it could be taken like a pill for instant effect, or dissolved in water for an effect over time and didn't add any flavor. Brian decided to do the latter as to not get Dave to realize he was growing so abruptly.
Despite being quite skinny, Dave went on a run everyday. At first, he didn't run with water, but knowing how this wasn't good practice, Brian made him bring a water bottle with him on his run, it quickly becoming routine for Brian to prepare the bottle. This served as the perfect opportunity to administer the supplement. That day, as Brian was getting the water ready, he put one pill into the drink and gave it to Dave as he headed for his run.
After about an hour, Dave returned from his run, and it quickly became apparent that the supplement took effect. He looked about an inch taller and had put on a bit of muscle, looking toned. Brian was glad that he only put one pill in as it looked to have quite an effect, "looking good little bro, have you been working out?" Brian asked as Dave entered the house.
"Not really" Dave responded clearly a bit confused as he looked in a mirror and noticed his new size.
It went on like this for a few weeks. About once or twice a week, Brian would add the supplement to Dave's water, and he would grow as a result. Brian had decided to stop the growth, being happy with the results. Dave was around 6' tall now, had some pretty good muscles, and was much more confident that he used to be. Brian also could have sworn that a few times he saw a bigger bulge in his running shorts, which he just mused was an extra benefit. Their dad being a personal trainer just said that Dave was experiencing a bit of a late puberty, something that Brain echoed to take away any suspicion of it being him. However, what Brian didn't know was that it was already too late. Brian went to bed that night content with his work, assuming that he was going to wake up like normal. However, when Brian woke up, he found that he was blindfolded and restrained to he bed.
He tried to break free of the cuffs that tied him to his bed, but found that they were far too strong for him to break. After giving up, he resorted to screaming for help, only to realize that he was gagged as well, only being able to let out muffled, almost moan like screams that would not be heard. He laid there waiting for someone to come, not having any other option. After a large amount of time, he heard his door open and close, followed by a locking sound. He again screamed and squirmed in his restraints, his naked body against the bed. He just heard what sounded like his brother chuckling. "You look good like that big bro" Dave laughed as he took off his blindfold so that Brian could see Dave standing there, shirtless, showing off his hairy muscles.
"You know, it didn't take long to figure out that you were the one who was growing me, after all, I always have been the smarter brother. I certainly didn't mind it to say the least, but I had to intervene when you decided to stop growing me. So I came into here while you were out and found this." Dave said as he took out the pill bottle and shook it a bit. "It was good that I did because then I could go to the shop myself and buy a bunch of stuff" He continued as he pulled out many bottles.
Dave then picks up the original bottle and strips to his tight underwear. Brian sees Dave's big bulge, much bigger than his own, looking to be at least 4-5" soft. He stares at it wide eyed in disbelief. Dave just laughs "You didn't know that it grew this too?" he said as he shook his bulge "Of course you didn't read the bottle, well you're going to see it grow much more, I thought it would be a good gift to you for growing me to get to watch my transformation into total god status" He said as he opened the bottle and swallowed the rest of the pills at once.
"Oh fuck, that feels so good!" He groaned as his voice deepened. Brian laid there watching in horror as he slowly grew. First was his height. Brian watched him get taller and taller, hearing his bones stretch as he slowly crept towards the ceiling. It seemed to never stop until he he almost touched the ceiling with his head, which is when the growth stopped for his height. Brian was shocked as he knew that the ceilings in the house were especially tall as out family runs a bit taller, so it was both horrifying and amazing that Dave stood there less than an inch from touching the 8'6" ceiling with his head. "The growth comes in waves" Dave grunted, his deep voice filling the room. His underwear looked painted onto his body, begging to break. "I wonder when they'll break, will it be my cock or muscles?" Dave added right before groaning loudly. "Here comes the next wave!" He said as his muscles started to inflate. They swelled bigger, quickly surpassing Brian's big muscles and his dad's. They kept on growing, adding on more and more mass, but no fat, showing off each and every bump and bulge in the skin. By the time it finished, he had surpassed anything Brian could have imagined, being the largest man that he had seen.
Immediately, the room was filled with an intense musk, as hair sprouted all over Dave's already hairy body, him look and smell even manlier. And finally, the final stage begun, marked by the loud ripping sound as his cock grew past the point of no return, shredding his poor briefs. His cock was already at least 8" soft when it was freed from its fabric prison, and was growing rapidly. It got longer and thicker, passing the thickness of not only Brian's wrist, but a soda can as well. While this was happening, Dave's balls were also swelling larger, and his sack dropping lower to accommodate their size. By the end of the transformation, his cock was at least 22" soft and a bit ticker than a wine bottle.
"You liked that big bro? Although I guess you're not big compared to me anymore" Dave asked laughing. Brian was too shocked to respond, not knowing what to do, and still wondering what Dave was going to do to him. "Wait here" Dave said as he left the room after grabbing a pill bottle. He came back after only around 30 minutes, and walked up to Brian and took off his gag. Brain was about to speak when Dave commanded "Don't speak unless prompted, understand?"
"Y-yes" Brian feebly responded.
"Yes, sir" Dave corrected. "Now, there's going to be a few changes around here, from now on, I'm the man of the house, everyone under this roof follows my orders, I've already worked this out with Mom and Dad, these pill making them nice and obedient" Dave said shaking the bottle in his hand. "My body has some new needs now that its like this, mainly this" Dave said as he grabbed his huge cock and shook it. "It needs someone to serve it, a personal servant for me, and specifically my cock, and since you were the one who initially grew me, I decided that you're going to take that role, serving as my personal cum dump, how do you feel about this Brian, or should I say slave?"
Brian was at a loss, feeling weak but also mad and angry that his brother was not only bigger than him, but had the nerve to treat him like a slave, however, he tried to remain calm and answered his question. "I don't think our parents would be okay with this sir" He said, confident in the fact that their conservative parents wouldn't want their athlete son to be demeaned in any way, let alone become a cock slave to their gay son.
"Don't worry about them, like I said, I've already taken care of them, we've agreed that it's best that you're my personal whore" Dave replied.
Brian was at a loss now, he seemingly had no way out. How would he be able to escape, or possibly adapt to his new life. "It's okay my slave, I can tell you're worried, but I didn't want you to be my sex toy without your consent, so I'll let you decide for yourself, but first..." Dave trailed off as he went to grab something. While he was doing this, Brian felt happy, he would just simply deny Dave's ridiculous proposal. This happiness was short lived as Dave walked to Brian's side, holding a small pill. An immediate dread filled Brian as he had no idea what the pill would do. "I didn't want you to make a regretful decision, so i thought this would help" Dave said as he forced Brian's mouth open and put the pill inside, keeping it in as it dissolved.
Brain's head filled with a fog. All of his thoughts of being straight and wanting to fuck girls disappeared, they were replaced with images of men. Tall, muscular, hung, and hairy men, all just like his brother. Additionally, any idea of topping also melted away, Brian quickly coming to the conclusion that he was meant to bottom, to serve alpha males, just like the one standing before him. Then finally, he felt a hunger, deep in his ass and throat. He hungered for the thick creamy cum that only a true man could give, no longer needing any other food or nourishment, only cum.
As all this happened, Dave removed all of Brian's restraints and went to stand at the end of the bed. As Brain came back to his senses, I sat up and looked at Dave. "Good, now it's time to make your decision, if you don't want to be my slut, then leave this house, but if you do, I will be downstairs with Mom and Dad eating dinner, you will crawl under the table and suck my cock. Doing this will mean that for the rest of your life, you'll be my personal cum slave." As Dave left the room, Brian felt his final transformation occur, his throat and ass loosening to be able to accommodate Dave's new cock. He made his decision and walked down stairs, got on his hands and knees, and crawled under the table in between Dave's big legs and started to eagerly suck his cock.
"Man, you were right, he's a total fucking slut now, good thing we have you to feed him" Brian heard his dad say.
"Yep, I'll make sure that he's always nice and full of cum" Dave said as his cock hardened to its full size of 30" and grabbed the back of Brian's head, quickly forcing the entire cock down his throat, marking Brian as his bitch.