Some Big and Round Fun!

Bowser has just returned to his castle after his time at the café with Peach. He quickly hurries out of his Koopa Clown Car to find Kamek. He stretches his way inside and finds Kamek.

“Welcome back my Stretchyness. How was it with Princess Peach?”

“It went very well~”

“That’s good to hear my Lord!”

“But something happened during it that I have to show you, Jr, and Dusty! So fetch them and bring them to my throne room for me.”

“Why certainly.” A bit surprised by this sudden order. “What is it that you want to show them so badly?”

“Heheh. You’ll see soon~” He gives him a smirk then leaves.

Everyone arrives to the throne room. “Well, what do you want to show us?” Kamek asks Bowser.

Bowser proceeds to stretch his arms around. “Look at the sleeves of my shirts they’re stretching along with my arms!”

Kamek and Jr are shocked by this.

“Woah!” Jr sounding amazed.

“What an interesting development of your rubbery powers!” Kamek says.

Dusty looks at everyone clearly confused and says. “Wait all of you have only just now noticed this!?”

“What?” All three say in unison.

“Each time he was flattened his arm bands and collar flattened and shaped with his body.”

They all think back and realized that Dusty is right.

“Ahem. Well anyways.” Bowser retracts his arms back to normal. “It would seem that anything that I wear stretches with my body.”

“It certainly seems to be the case my Stretchy Lord.” Kamek replies.

Jr suddenly gasps with excitement. “What if you wore a costume like the villains and heroes wear in the comics I like to read!?” He says with such excitement and enthusiasm.

“Haha! Now that does sound like a fun idea, but maybe for another time.”

“Aw… ok Dad.”

“Besides I have something else I wish to do anyways.”

“Like what?”

“It’s time to finally see what happens when I fill myself up with a lot of air!”

Jr gets excited, Dusty just stands there listening, and Kamek says. “Would you like me to start prepping for today then?”

“Yes, but I wish to do this tomorrow. Also I’d also like to try it with water too to see what happens.” He proceeds to go over his plans and ideas with everyone. “Well with that all sorted out now I shall see you all tomorrow!”

“Understood!” They all reply, Dusty’s being quieter than the others.

We skip ahead to the next day in the late morning. Bowser, Jr, Kamek, and Dusty are all out at the testing grounds outside ready to get things started. Dusty leads them to a newly built area that’s fenced off and covered with netting and a what looks like pump stand inside of it with hoses attached.

Dusty says. “Here we are my King.”

“Well done Dusty! Yet again you’ve done a fantastic job already! Anything you need to tell me about how it works?”

Feeling very flattered Dusty says. “Why thank you! Ah yes. You just turn the dials to turn them on. Turning them further increases the rate of flow, so more air or water quicker the further you turn them. Also, the enclosed netting is to make sure any wind doesn’t potentially blow you away and there is a drain on the floor for the water.”

“Sounds good to me!”

“Can I come in with you?” Jr asks Bowser.

“Sure!”

“Yay!”

“You two stay on standby incase you are needed.” He points to Kamek and Dusty. They nod.

They both enter and walk up to the pump. Bowser grabs the air hose, puts it into his mouth, and turns it on. It takes a moment before he feels his belly beginning to expand.

“Look it’s getting bigger!” Jr. shouts excitingly.

Bowser lets his belly get nice and round before he turns it off.

“Hm…” He ponders for a moment.

“What is it?” Jr. asks.

“This feels surprisingly underwhelming…” Sounding a bit disappointed.

“Well… how about this!” Jr. begins drumming his dads belly making noises similar to an exercise ball while doing so.

“Hahaha! As fun as that is I have a different idea.” He says as a smirk crosses his face. He tells his son to turn it on then off on his signals. Jr. gets into position.

Bowser gives the signal and Jr. turns on high. He suddenly feels his belly swell very quickly now feeling great tension in that area. However he doesn’t have long to process this new sensation as he feels the rest of his body beginning to quickly expand.

Bowser gets worried and tries to signal his son to stop. He misreads his signal and ends up turning it up to max. The next thing he knows FWOOMP! He suddenly becomes an enormous air filled balloon with his hands, feet, and head poking out. His cheeks and tail are also big and puffy now.

“AH!” Jr. quickly turns the air off.

Everyone asks if he’s alright. Bowser replies with a “Hmph!” as the hose is still in his mouth. Jr. pulls it out.

“Puwa! Well my entire body feels like it’s under immense tension, but other than that I’m fine.”

“Is it discomforting?” Kamek asks.

“No, it’s just different and new, so I’m just not used to it yet. Let me sit here like this for a bit to get used to it.”

“Alright!” Kamek and Jr. reply as Dusty just nods while closely watching Bowser curiously.

Bowser spends the next roughly ten minutes like this getting familiar with this new feeling of tension. In that time he decides that he likes this new feeling. He also tries to move but is only able to wiggle his hands and feet. A wind gust also rolled him into a corner of the netting at one point.

“Alright I’m satisfied now!”

“Would you like some help with getting back into shape?” Kamek asks.

“I’d actually like some help to get the air out of me as I don’t know how to do it myself yet. So come in here and give me a squeeze to get the air out.”

The three of them enter and push into him while he holds his mouth open. It’s slow going at first but after a strong shove in particular Bowser suddenly rockets into a different corner of the netting and rapidly deflates, screaming as it happens.

“AAAAAHHHHH!!!” He’s now in a deflated state on the ground. “Well that was something haha!” He quickly picks himself up off of the ground.

“Hm… this is interesting.” He then puts his thumb into his mouth and puffs himself back into shape.

“Now it’s time for the water test~” Eagerly rubbing his hands together.

“Can I turn the water on too?” Jr. asks.

“No. I’ll handle this myself so all three of you can wait outside.”

“Aw ok…” They go to watch from behind the netting.

Bowser puts the water hose in his mouth and turns it on. He immediately feels the water moving around inside of him as his belly fills with water. As his belly area grows larger he feels just how heavy it is. His belly stretches down to the ground and begins to spread outward.

“Wow! This feels entirely different and… so nice?” He thinks to himself. After some more water he turns it off and pulls out the hose. He touches his water filled belly noting that it feels exactly like a water balloon. The water moves around inside of him as he does this causing him to smile with enjoyment as he feels it sloshing around.

He suddenly snaps back to reality when his son asks. “How does it feel!?”

“Ah! It uh feels like a giant water ballon.”

“Cool! Can I feel it?”

“Sure. I’ll come over to you.”

He waddles and huffs and puffs his way over realizing just how heavy all this water weight is. By the time he gets there he’s out of breath.

“You alright?” Kamik asks.

“I’m fine.” He says between breaths. Jr. at this point reaches through the netting and feels his belly.

“It does feel like a water balloon.”

“Well I’m satisfied with things here for today.”

“Already!?” Kamek says surprised.

“Yes.” He stretches his arms to scoop up his belly and does a controlled squeeze. He spits out the water in a steady stream kind of looking like a decorative fountain while doing so. He finishes and exits the netting.

“We sure have learned a lot of what I can do now haven’t we?”

“Yes we have.” Kamek replies. “Yeah!” Jr. cheers. Dusty nods affirmably.

“But there’s still one more thing to do.”

“What is it my Stretchyness?” Kamek asks.

“We have a special outfit to put together for myself now!” He looks at Jr. with a smile.

Jr. gasps. “Really!?”

“Yeah I really liked the idea and I have some thoughts about it already.”

He shares some of his thoughts about it as they head back to the castle.

What an Interesting Development.

These wonderful arts where made by  GrichyinkReally
I hope that you liked this silly thing I've done. Comments are welcome. Please keep them SFW.