--Disclaimer---
This story is entirely fictional and doesn't/shouldn't represent any real life situations. It is strictly for entertainment purposes.

Chapter 7: A Matter of Time

“Wait, you mean you actually did it!? Sonic gasped. 

“It's not permanent of course, that would be impossible…but yeah, it should work for just one night.” 

Sonic leaned forward and kissed Tails’ forehead. “One night is perfect, my little genius. I'll swing by for dinner then, later!” 

A casual wave and Sonic sped out of Tails’ workshop. Tails clenched his fists and jumped up and down with excitement. It all started with a crazy dream one night where Sonic had suddenly become younger. The same age as Tails in fact. While the dream was mostly a fun and fascinating narrative, Tails did wonder how a younger Sonic would handle intimacy. 
It had taken over 9 months but Tails had finally managed to invent a serum to temporarily regress any living creature's physical traits for a short time. Using nanobots he was able to do what he called “quantum suspension.” This allowed him to program his nanobots to mimic the cellular age of another organism. Using his own DNA as a base, the nanobots in a serum could be injected to give a creature the physical traits of being younger. It was only temporary though as the bots had a limited power source and could only maintain the illusion for 12 hours at most.
After several tests on various subjects Tails was confident he could safely use it on Sonic for an evening of fun…and he couldn't wait to see what the teen would look like in a kid's body.

… …

Slipping off his shoes and laying on the couch,  Sonic tried to relax as Tails prepared his serum. The two had just finished dinner, and were eager to get intimate for the night. Poking Sonic's arm with a needle and pressing the plunger down, Tails’ special nanobots quickly went to work. 
“It'll take a few minutes to kick in.” Tails told him. “I'll go get things ready in the bedroom. Come find me once it's working. 
Leaving Sonic to rest, Tails headed for his bed. 

As Sonic lay still with his eyes closed, he could feel a strange tingling sensation throughout his whole body. It wasn’t at all painful, but slightly uncomfortable at times. After 5 minutes the sensation stopped and he was left feeling normal again. Opening his eyes he looked down at himself. His gloves and socks seemed to be hanging on him VERY loosely. His quills were a slightly lighter blue as well. Sitting up, his feet didn't even reach the floor. His socks slumped down where he could easily just wiggle his ankles and they dropped off. Jumping down from the couch, his gloves fell to the floor effortlessly. Looking at his shoes, Sonic could tell they were now twice the size of his feet. 
“Whoa!” Sonic gasped. “Wait, wha?” Even his voice had changed. It was slightly higher pitched and nasally. Chuckling to himself, he looked down at his groin. He wondered just how much smaller he was going to be. Shrugging he slowly headed for Tails’ room.

Meanwhile, Tails eagerly laid on his belly, kicking his legs as he awaited Sonic. While he had a little idea what the blue hedgehog might look like, nothing could have prepared him for the adorable ball of quills that stepped into view. The fox's jaw dropped and he immediately blushed. Sonic was so cute!
His lighter blue fur and quills perfectly complimented his emerald eyes. He was shorter, rounder, and his smile was intoxicating. Leaping from the bed, he ran up to him gleefully. Reaching Sonic, Tails couldn't help but laugh. He was now taller than his older partner. Not by much, but enough that he needed to look down into his eyes. 

“Hehe, wow Sonic! You look great!” Tails exclaimed. “Like…really great!”

“Glad you think so, little bud…” Sonic tried to stay his confident self as he leaned back on one heel and folded his arms. However, seeing how much taller Tails was than himself now, calling him little seemed out of place. 
“Heh, guess I'm the little buddy now.” 

“You sure are,” Tails mumbled, reaching his hands up under Sonic's chin. “You're perfect.” Leaning in Tails parted his lips. Sonic smiled, closing hisceyes and accepting Tails’ advance. Their familiar tongues meeting as their evening intimacy began, a swelling of emotions boiled through them both. Sonic reached his hands up, but could barely get around Tails’ back. The young fox immediately could tell he would be dominating Sonic all night. Even the hedgehog's tongue was smaller and weaker than he was used to. Breaking from the kiss, Tails looked lustfully at Sonic flush expression. He could tell that even kissing was getting him more turned on than usual. 

“Huff. Huff. T…Tails,” Sonic said, catching his breath after their extended kiss. “I feel…hot.” 

“You're super hot, Sonic. Are you ready for this?”

“Y…yes.”

Tails couldn't believe how timid Sonic sounded. It felt like their first time all over again. Smiling, he bent down and scooped the hedgehog up walking him to his bed. Gently placing him on the soft sheets, Tails tossed his gloves off, and ran his fingers over Sonic's chest. He was mesmerized by Sonic's younger body. Every curve seemed to better fit his grasp than ever before. As Tails explored, he felt his little foxy dick growing out of his sheath. Licking his lips, Tails quickly became aroused by just touching Sonic's body. It wasn’t long before his 4 inch knotted cock was proudly standing out and its tip tickling the sheets. 

Sonic's breathing was heavy as he let Tails run his hands all over his regressed form. Every gentle touch sent shivers through him, as it seemed the serum made him more sensitive as well. As Tails worked further down, Sonic watched closely, face flush with embarrassment and lust. Unlike his older body which had a thick tuft of pubic fur covering his slit, his younger body was more exposed. As Tails spread his legs wide for a better view, his young hedgehog slit opened slightly inviting the fox's touch. 

“Wow Sonic!” Tails gasped, followed by a giggle. “I wish I met you when you were like this.” Not wasting another second, Tails traced the edges of Sonic's quivering slit with his thumb. Sonic let out a soft whimper as his new extra sensitive slit was teased. The feeling pushed the tip of his dick out almost immediately, which Tails was quick to begin rubbing. Pinching the tip lightly, Tails giggled as Sonic grew hard right in front of him. 
After a few seconds the fox was shocked to see Sonic was already at full mast.
“Haha, no way. It's smaller than mine now!” 

“Huh?” Sonic tipped his head forward and looked at his dick. “Awe man!” Sonic whined, forgetting just how generous puberty had been to him. His previously impressive 8 inch cock was now a measly 3 inches. 

“Guess that means I can finally do this!” Tails quickly opened his mouth wide and closed it down over Sonic's entire cock. The little blue hedgehog gasped followed by a satisfied moan. His hands turned to fists, balling the bedsheets in the process. Tails slurped loudly as he happily rolled Sonic's length across his tongue. He couldn't believe he was able to pleasure Sonic all at once. Tails hummed happily, feeling his lover squirm. Despite the younger body, Sonic's cock tasted as delicious as ever. Though the age regression had severely stunted the hedgehog's precum production, his slit was still wet enough to compensate. When Tails pushed his muzzle down, he slid his tongue into Sonic's tight boyish slit tasting every delicate drop. 
Sonic's moans were high pitched and whiny which only further fueled Tails’ desires. The young fox's boyhood throbbed, dripping streams of precum against the side of the bed where he was crouching. Confidently keeping Sonic's left leg propped open, Tails reached down with his right and gently tugged on himself. 
“Mmmmmm. Mmmmmm. Mmmmmmh,” Tails couldn't get enough of Sonic's cock. He was relishing every moment he could, knowing this was the first and last time he could fit the whole thing in his mouth. 

“Tails! AH, AHHHHH!” Sonic's cute voice suddenly cried out. His legs bent up and he bucked his hips, pushing Tails off of him. “Huff. Huff. UNGH!” The tiny hedgehog's whole body tensed and his cock throbbed wildly, but not a single drop of cum escaped his body. Tails’ eyes widened as he realized the age regression had taken Sonic back to an age before he could produce semen. The blue hedgehog could only have a wildly intense dry orgasm. 

Crawling onto the bed beside him, Tails rested his stiffness on Sonic's left leg as he rubbed the hedgehog's chest. Gently rubbing his short blue fur, Tails stayed with him as his tiny body was wrecked by a fruitless climax. 
“Sorry Sonic. I didn't know you were too young to cum at my age.” Tails smiled, feeling a little regret, but also a deep sense of pride from how quickly he brought Sonic to the edge. 

“T…Tails…I…I love you, Tails.” Sonic could barely speak. He was completely out of breath. His regressed age had given him one of the best orgasms he'd had to date! Despite already being exhausted, he knew Tails would want more. He wasn’t sure if his small body could handle their usual routine, but despite his extra sensitivity…or perhaps because of it, he desperately wanted more. 
“T…Tails please…” 

“Hrm? What is it, Sonic?”

“F…fuck me Tails! Please…I've gotta know how it feels in this body!” 

“Oh Sonic!” Tails blushed. Sitting up he kissed Sonic gently on the lips. “I'll be sure to make you feel really good..”

“T…thanks.” 

Crawling down to Sonic's waist, Tails straddled Sonic's head. Letting his knotted boyhood dangle in the hedgehog's face, Tails licked under his partner's slit and down to the tiny puckering tailhole. Sonic gasped, lifting his hips for Tails to have better access. Waiting no time, the young fox gleefully lapped across Sonic's hole. The tiny blue hedgehog closed his eyes and panted, feeling his foxy lover preparing him. As Tails worked on loosening him up, strings of precum dribbled into Sonic's opening mouth. 

Once Tails felt satisfied that Sonic was ready. Tails moved to the side, and instructed him to get on his back. Though tired, Sonic did as he was told, spreading his legs, inviting Tails to penetrate him. A wide grin cut across Tails’ face and walking across the bed on his knees, he aligned his throbbing boyhood against Sonic’s tailhole. Pressing the tip against him, Tails grabbed the hedgehog's hips for support and pushed forward. 
Sonic yelped as he felt Tails’ cock slip inside him. With his smaller, younger body his young lover's boyhood felt huge! He could barely stand the pressure of having his little tailhole violated by his little buddy's canine member. Every throbbing curve pressed hard inside of him. He could feel Tails’ pointy tip aggressively prod his shrunken prostate, milking a few drops of precum out of his little cock. Sonic quickly wrapped both legs around Tails’ back as he felt all 4 inches inside him. The young fox's knot was now firmly resting against Sonic’s tailhole, his lover's boyhood fully inside 

Tails grunted, gritting his teeth. Sonic was so much tighter now that his body was the same age as his own. He wondered if he was when bottoming for Sonic, if this was how good it felt for him. Every inch of his cock was being squeezed hard by Sonic's tiny body. Despite having plenty of lubrication from his ample precum, Tails still found it hard to start pumping. However as Sonic eventually got used to it, the young fox was able to speed up until he was giving Sonic a moderate pounding. 

SHLUCK PLAP SHLUCK PLAP SHLUCK PLAP 

The two boys were intoxicated by pleasure, every thrust sending electric sensations through them. With the extended time Tails had edging himself closer and closer to climax he was already about to burst. 
“F…ah! Sonic I…I'm gonna cum!” 
Sonic gasped and quickly pulled hard with his legs forcing Tails' now very swollen knot past his already tightening tailhole. 

POP

“AAAAANNNGGHHH!” Both boys shouted. Tails wasn't planning on trying to knot him, having already felt just how tight Sonic's younger body was. However Sonic wasn't about to let his temporary physical traits go to waist. He wanted his lover's cock…all of it! Despite the pressure now dipping into pain, Sonic loved every second of it. Tails' body shivered as a massive burst of cum erupted into Sonic's tiny body. 
Since the two first became intimate, Tails' body had slowly been producing more and more cum. While it was still mostly thin, he was now squirting a solid 5 streams of it. Every splash into his gut, Sonic let out a short gasp, his body warmed by the fox more and more. Gently tugging his knot as he finished cumming, Tails could tell they'd be stuck together for a long time. Perhaps even until morning. 

Catching his breath, Tails wrapped his arms around Sonic's back and rolled to the side hugging him close. He could feel Sonic's boyhood had gotten hard again, as it poked his fur. Their breaths now syncing, the two quickly fell asleep, unified by their love. 

… … 

By the next morning Tails’ cock had slipped out of Sonic. The blue hedgehog was back to his full sized teenage body as normal. Awakening nearly at the same time as the morning sun shone on their naked bodies, the two smiled looking deep into each other’s eyes. 

“Hey,” Tails whispered.

“Morning, little buddy,” Sonic replied. “Thanks for last night.” 

Tails blushed and giggled. “Hehe, you're welcome, Sonic. Glad you had fun.” 

“You think next time we can try it the other way?”

“Huh?” Tails said, pushing himself up on one elbow. 

“I wanna see what we have to look forward to when you grow up. So use my DNA and let's see how big you'll get.” 

Tails was stunned. This was quite the suggestion first thing in the morning and surprisingly not something he considered. “You…really?” Tails was immediately interested in the idea. Based on his research it should be possible for sure. 
“O…Okay!!” Tails shouted excitedly. “I'll get started right away!”