Frank N. Stein’s monster

by Musclesaber

Dr. Franklin Nelson Stein has finally done it. He’s perfected a muscle growth formula that he plans on using on his husband Luke. Little do they know how Luke’s body will react to the formula after Luke ingests more than he intended.

2,826 words Added Oct 2021 10k views 4.8 stars (13 votes)

You may be looking for the following similarly named story: Frank by Anonymous.

Vote on this story Jump to comments Suggest tags for this story Print / PDF Share Update history More like this Symbols Unit conversion Report a problem


Chapter 1: The Formula

It was a stormy and cold night in a small town in Ohio where a man had been tirelessly working on his newest project. Dr. Franklin Nelson Stein had been trying to perfect a new steroid that was supposed to enhance muscle growth ten times better than any steroid while avoiding the negative side effects. With a doctorate in pharmaceuticals, he had created multiple drugs that had done excellent on the market, but this one was different. He had made this one specifically to help his husband.

He heard the lock on his front door twist and in walked in a tall lanky blonde man. “Honey I’m home.” This was Frank’s husband, Luke. At 6’4, Luke had next to no muscle or fat on him. He was 150 pounds soaking wet, which he was from the rain outside. Frank came out of his study to greet him.

“Hey babe, how was work?” asked Frank as he got on his tiptoes and kissed Luke on the lips. At 5’6, Frank had a much similar body type to Luke’s, but on a shorter body. Luke leaned down and kissed his husband and then began taking off his wet coat.

“Not the best. There was a major pile up on the freeway and there were so many injured. I did get to save a few, but a lot of them didn’t make it.” Luke slugged himself over to the living room where he sat down and let out a sigh.

“I’m so sorry honey. I know these nights are always tough on you,” said Frank as he sat down with Luke on their couch. His hand rubbing his back in an attempt to comfort the tall man. “Well I do know something that might cheer you up. It’s just about done.”

“It is?!” said Luke as he lit up like a kid on Christmas morning. “That’s wonderful, Frank.” Luke practically tackled Frank with kisses as he was too excited to speak.

“Hold you horses, big guy. I’ve still got a few more tests to do before you can have it, but I can have that done by the time we have dinner.” Frank returned Luke’s kisses and pushed the big lug off of him.

“Well then, don’t let me keep you! Go go go!” Luke got off of Frank and jumped for joy as Frank got up as well.

“I didn’t have time to get dinner ready, so just Doordash something. And make sure it’s a lot of food. The formula is best taken before eating.” Frank winked at Luke and went back to his study. He started to get back to working on his formula and making sure it’s perfect for Luke. Meanwhile, Luke was on his phone ordering a plethora of food for the two of them from their favorite Mexican food place.

Frank started to get calculations on Luke’s exact BMI and calculating the portion size needed for a safe trial. Frank got out a syringe and started to measure out how much he needed, but Frank, being overly excited, pricked his finger with the needle by mistake. “Fuck, ouch.” He set the needle down and ran to clean it up. It had broken the skin, but there wasn’t a whole lot of bleeding. He dabbed away a little bit of the blood, then heard Luke’s voice.

“Everything okay in there?” said Luke from the other room.

“Everything’s fine, honey.” Frank picked up the liquid and started walking to the kitchen. “I’ll just let him drink it,” said Frank to himself.

After the tests were complete, Frank emerged from his study and into the kitchen with a vial of blue liquid. “Here it is Luke, the solutions to your body problems.” For years, Luke had been a regular at the gym and studying the anatomy of the body. He had studied kinesiology during his undergraduate degree and was now an EMT on track to beginning med school with a focus in muscle development. The only problem for Luke was he could never grow any muscles of his own. No matter how hard he tried or whatever he took, he stayed a string bean.

“Gimme!” Luke practically charged at Frank to try and get the vial from him.

“Uh uh uh, let me do something first.” Frank took out a glass from their cabinet and filled it with water. He set it down and then took out an eye dropper. He put it in the vial and sucked a bit of the blue liquid up then moved it over the water and put 4 drops in. He put the rest back in the vial and handed the cup to Luke.

“That’s it? That’s all I get?” asked Luke as he picked up the glass. He swirled it around and you could barely see the tint of the blue anymore in the water.

“That is all that you’ll need by my calculations. Any more and I don’t know what might happen to you.”

“Maybe I could just have a little more? Just another couple more drops, just to see if it works,” bargained Luke. Frank didn’t answer and simply gave his answer in the look he gave him. Luke frowned and knew he wasn’t gonna get Frank to budge. He lifted the cup to his face and started to chug the water. He downed the glass and let out a little burp when he finished. “So when will it kick in?”

“Give it an hour or so, but we have to get you to the gym to start to see the real results. We can do that tomorrow though. Tonight, I just want to be with my husband.” Frank got on his toes again and Luke leaned down to kiss him. “What did you get us by the way? I’m getting pretty hungry myself.”

“It’s taco Tuesday, babe. I got us a lot of food that I’ll eat to grow these muscles big and strong.” Luke brings up one of his arms and flexes his tiny bicep. “And if I don’t finish it, we can reheat it later. But I ordered it a while ago. Guess the delivery driver got held up in the storm.” Luke reached for the vial on the counter and looked at it. “So there’s really no chance, I can get anymore? It felt like nothing.”

“Luke, I don’t want you having anymore. This hasn’t been properly tested and if you were to have a terrible side effect from overdosing, I could never forgive myself.” Frank said as he took the vial from him. “I’m gonna put this back in my lab and we’ll get all the results we need in the morning. I’m certain you won’t be disappointed.”

Frank walked back to his study to put the formula away, but on his way, the power in their house went out. Frank was in the dark and couldn’t see a thing. “Dammit, the braker must have gone out,” said Frank as he tried to navigate his house blind. He kept walking in the direction he thought was his study, but instead he hit a wall.

The vial got jostled in his hand and a bit of the liquid spilled out and onto his hand. “Oh no!” Frank started to frantically get into his study and find somewhere to put the vial. He found his desk in the dark when the lights suddenly turned on. He looked down at his hand and it was covered in the blue liquid. “Shit.” Frank immediately ran to their bedroom and took off all of his clothes and jumped into the shower to thoroughly wash off all of the chemicals.

“I got the power back babe. Is everything okay?” asked Luke as he came into their bedroom.

“Not really. I spilled the vial on my hand, and I have to get it off me.” Frank scrubbed and scrubbed his body, but the damage had been done. The formula he spilled landed on the cut on his finger.

“Is there anything I can do to help?” Luke started walking into the shower where Frank was.

“Not in here, but if you could be the best husband in the world and go put the formula in the refrigerator. I didn’t get the chance to do it after I spilled it on me.”

“You got it, babe.” Luke rushed out of their room to Frank’s study where he saw the vial sitting on Franks desk. He picked it up and opened the fridge where Frank kept all of his chemicals. “A little more wouldn’t hurt, would it?” Luke lifted the vial to his lips and threw it back. Easily drinking the entire contents of the vial. He looked at the empty vial. “Oops, maybe not that much.” Luke scrambled in the fridge and found a spot in the far back to put the empty vial.

Frank emerged from the shower clean and refreshed. He put on a new change of clothes and headed to the living room where he saw Luke sitting on the couch. “Thanks babe. That power outage surprised me a bit, it must be bad out there.” Frank came over to Luke and sat next him. Cuddling up against his side.

“I told you it was bad today. I feel bad for our delivery driver. I’ll be sure to tip him extra when they get here.” As Luke said that they heard a knock at the door. “Speak of the devil, I’ll get it.” Luke got up and opened the door to see an average sized man soaking wet on their doorstep.

“Here’s your order,” says the delivery driver as he handed Luke the food. Luke took the food and felt an odd jolt of energy as he did so.

“Thanks, sir. Here’s a tip.” Luke hands him the tip and Luke’s body jolts again. The delivery driver looks exhausted as he starts walking back to the car. “Have a nice night!” shouts Luke as he shuts the door. “Food’s here.” Frank looks over to see the multiple bags Luke is carrying.

“Wow, you weren’t kidding when you said you got a lot of food.” Frank gets up and goes to the kitchen with Luke. They lay out the spread of all the tacos and the fixins. The two sit down and Luke starts to tear up the tacos. He quickly eats one taco and immediately starts on another, then another, then another, until he’s devoured 10 tacos before Frank has even finished two.

Uuurrrppp! Woof, that was a lot of food.” Luke pats his slightly bloated stomach. Frank looked over at Luke and he was looking…bigger. His shirt was fitting a bit snugger, his pants a bit tighter, and his head a bit closer to the ceiling.

“Hmm, you’re already looking bigger, honey. This is odd. You shouldn’t have gained any size by now,” exclaims Frank. Luke looked a little worried as Frank talked.

“Guess my body is just responding well to your formula. You did such a good job, babe.” Luke gets up and starts to clean up. Passing by Frank and giving him a kiss on the forehead.

“I guess so, but it is getting a little late. After the dishes, you wanna head to bed? I know you’ll be ready to go to the gym tomorrow morning to test out your new body,” said Frank as he got behind Luke doing the dishes at their sink. Frank could feel some new definition in his ass and back.

“That sounds great, babe. I’ll finish these up and meet you in the bedroom.” He pushed his butt back into Frank and almost bumped him down onto the floor not knowing his strength.

“Woah babe, that ass is definitely getting bigger. Be careful before you knock me over.” Frank gives Luke’s ass a slap and heads to their room. Luke soon followed him back to find Frank naked on their bed. “Maybe we see what that ass is made of now.” Frank’s pulsing 7-incher waiting for Luke in bed. Luke licked his lips and quickly undressed as he got in bed. He hopped on top of Frank giving him a kiss and grabbing his cock.

“Fuck babe, are you gonna miss having the bigger cock in our relationship? Because I know this little guy is gonna grow huge.” Luke’s own 5-inch cock was getting hard as the two made out. Their bodies grinding up against each other.

“I can’t wait. You’re gonna get so fucking big, Luke.” Luke got up off of Frank and presented his toned bubble butt to him.

“Tell me how big I’m gonna get,” said Luke as Frank got up and started to tease Luke’s hole with his cock.

“Where do I begin? You’re gonna be huge, babe. Absolutely massive. You will tower over everyone. I know you already to that to most, but even people that are 6 feet tall won’t even come up to your massive pecs.” Frank began to push his cock into Luke. The two of them both moaned and Frank continued. “And what a massive chest it will be. For one thing, you’ll be wider than our king-sized bed. Unable to walk through doors without side stepping them. But your pecs will be so thick and juicy that you won’t be able to fit that way either. Your pec shelf will stick out two feet away from you and each be as big as pillows for me to sleep on.”

“Fuck, Frank. Keep going.” Frank started to thrust into Luke and Luke moaned in appreciation.

“Your arms are going to be like actual cannonballs. They’ll be bigger than your head and could easily lift our bed up without even breaking a sweat.” Frank kept grunting as he thrusted into Luke. A loud smacking sound could be heard like the thunder outside with each thrust. “And those abs will be legendary. Rows upon rows of abs. Too many for us to count.”

“Fuck babe. I don’t know how much I can hold it.” Luke said as he could feel his cock leaking pre on their comforter.

“You should be able to hold it now. Because when you get balls that are bigger than soccer balls, it’s gonna be hard to have you not cumming every second of every day. And what cock you’ll be cumming from. That cock will be bigger than your current arm. At least two feet long and thicker than a two-liter bottle of soda. I’m gonna need to take the formula just so my ass can keep up.”

“I’m gonna be so big. Bigger than anyone who’s ever existed,” said Luke out of breath. Frank’s thrust getting faster and harder as he kept speaking.

“And then some babe. You’ll put body builders to shame with how big you get. We might need to move out of this house because it won’t be able to properly hold a titan like you.” Frank leans forward and grabs Luke’s hips to shove him deeper into him. “You’ll be a god amongst men. A living wall of muscle. The sexiest man to ever live. And I’m just gonna keep making you bigger.” With that last word, the two of them started cumming. Frank shot load after load into Luke’s ass and Luke painted their entire comforter with his cum.

The two of them collapsed on top of each other after their intense orgasm. Frank pulled out of Luke and got up to go get a towel and a different comforter. “Will I really get that big babe?” asked Luke as Frank started to wipe cum off of himself.

“One can only hope you do. Well, actually I’m hoping you get much, much bigger than what I described, but that remains to be seen how effective my formula is.” The two of them changed out the comforter and cleaned themselves up.

“With my genius of a husband, I’m sure I’ll get huge.” Luke kissed Frank on the forehead and the two got in bed. Luke wrapped his arms around Frank spooning him. Frank reached over and turned off the light on their bed side table.

“Good night honey. Sweet dreams,” said Frank.

“Night baby. Love you,” replied Luke and the two of them dozed off into a deep sleep, unaware of what changes tomorrow would bring.

2,826 words Added Oct 2021 10k views 4.8 stars (13 votes)

Vote on this story Jump to comments Suggest tags for this story Print / PDF Share Update history More like this Symbols Unit conversion Report a problem




More Like This

Supersized by Musclesaber After an experiment gone wrong, Max unexpectedly grows into a giant. After being saved by his superhero crush, Amplified, the pair tries to get the giant man’s growth under control. 2 parts 5,286 words Added Nov 2020 14k views 5.0 stars (9 votes) •Cock Growth•Huge Balls•Huge Cock•Hyper Cock•Cum inflation•Hyper Cum•Muscle Growth•Belly Growth•Getting Taller•Giants•Superhero/Supervillain •M/M

Let’s play a game by Musclesaber Four men wake up in spandex body suit with a familiar board game laid out in front of them, only to mind a masked man willing to fulfill their wildest dreams if they're willing to play. 1,999 words Added Nov 2023 6,123 views 4.5 stars (14 votes) •Cock Growth•Muscle Growth•Butt Growth•Forced Growth•Size Increase•Stories with Images •M/M•M/M/M/...

The best instructions are those that are clearly stated by Ziel Marty talks his super smart friend into whipping him up a special potion that will help with his little problem. 5,194 words Added Jun 2016 23k views 5.0 stars (11 votes) •Cock Growth•Huge Balls•Huge Cock•Hyper Cock•Hyper Cum•Infectious •M/M

The cock-off by Armie Lingo In the gym locker room, Nick and Joe get the chance to admire Cock-Off champion Steve up close. 3 parts 5,295 words Added Oct 2005 26k views 5.0 stars (11 votes) •Cock Growth•Huge Balls•Huge Cock•Hyper Cock•Hyper Cum•Muscle/Strength •M/M•M/M/M

Cody and Todd by klj Little green pills lead to roommate fun. 2,654 words Added Jun 2005 22k views 5.0 stars (14 votes) •Cock Growth•Huge Cock•Cum inflation•Straight to Gay•Increased Libido •M/M

Rapeenzel by Ziel Ziel got to thinking about old fairy tales and thought, “You know what these stories need? More gay sex and macro-dongs!” So he threw in a touch of cutesy fluff and some soft CV elements. Lots of sappy romance and monstrous dongs ensued. 6,583 words Added Sep 2015 25k views 5.0 stars (8 votes) •Cock Growth•Cock Vore•Huge Balls•Huge Cock•Hyper Cock•Prehensile Cock•Hyper Cum•Always Shirtless•Medieval(ish) •M/M

Simon says by BRK My goofy, fun-loving shop owner loves staging these ridiculous competitions with us, but this latest one is definitely the craziest. 2 parts 7,732 words Added May 2013 Updated 30 Jun 2017 23k views 5.0 stars (10 votes) •Cock Growth•Huge Cock•Hyper Cock•Extra digits•Multi-abs•Multicock•Multiarm•Multilimb•Muscle/Strength•Getting Taller•Size Increase•Suggestion

Student body president by BRK Being a warlock at school can be a pain—especially if everybody knows. 2,906 words Added Sep 2004 25k views 5.0 stars (4 votes) •Cock Growth•Huge Cock•Self-suck•Multicock•Muscle Growth•Muscle/Strength•Stretchy•Size Increase•Witch/Warlock/Wizard•Complete

scrollTop: 0

Share your upgraded-guy story at


For more on BRK’s Patreon click here or go to  (Credit: alfa27)