For years Mikey had always been the runt of the lair. Though in some ways understandable, given he was the youngest of his turtle bros, still, even during his late teens, Mikey only stood at 5’4” and that was when he was standing on his tiptoes. His short stature forced the orange-banded turtle to ask for either 5’11” Leo, 6’1 Raph, or 6’4” Donnie for help reaching things around the kitchen or lair, resenting every request as a patronizing assault on his capabilities.

During training, despite his flexibility and nimbleness, he was always overpowered by his bros. While Donnie and Leo would go easy on him, out of pity, Raph showed no such restraint, using his thicker build to either hold Mikey at an arm’s length during hand-to-hand combat drills, stepping on his back during push-up drills, or simply hoisted him up under one arm sporadically throughout the lair just because he could, causing whatever Mikey was holding to loudly clatter to the ground though never drowning out the laughter of his older, taller, teasing bro.

The worst of the bullying, however, was whenever Mikey was playing basketball. He often liked to put on some headphones and shoot around on the hoop in the corner of the vehicle bay to clear his head, especially on days when it was too cold to ride the sewers on his skateboard. Yet, without fail, Raph would always saunter in and, despite Mikey’s protests, INSIST on playing one-on-one. Mikey never stood a chance, always bumped out of the way by Raph’s hips or elbows, slipped past his sweaty shoulders like a wet fish, or found himself face deep in Raph’s pits, chest, or crotch when Raph powered straight through Mikey for a loud dunk on the rusty hoop. It was always humiliating, and Mikey would gripe for hours about it to anyone who’d listen. Fortunately, Donnie always had a sympathetic ear.

Donnie, while soldering a circuit board or reframing a metal plate for the SHELLRAZOR, would nod and console Mikey while he rambled about his “short king” woes, wishing every day for just a bit of the height that his brothers had and he was cursed to go without. Every day was the same, almost like clockwork such that Donnie passively penciled it into his schedule as part of his “big bro” duties, but then one day, as Mikey belabored on a diatribe about Raph going out of his way to put Mikey’s cereal on the top shelf in the kitchen, Donnie paused as he heard a subtle, though persistent scratching sound. He glanced over at Mikey and saw that as he sat swinging his legs along the edge of the empty lab bench, his toes were ever so slightly grazing the floor.

That’s a first, Donnie noted to himself. Normally Mikey’s feet rocked back and forth with plenty of air space, but that altitude had disappeared: was Mikey getting taller? Over the next two weeks, Donnie noticed the subtle scratch growing more and more distinct until one day the sound stopped as Mikey was casually resting his feet on the floor as if he always had; unaware.

Well, given the impossibility of the lab bench shrinking… Donnie reasoned, confirming his earlier hypothesis, though that wasn’t the only thing he noticed. Mikey’s feet themselves seemed bigger too, as evident by the subtle indentations of his support straps pressing into his ankles and heel, ones that Donnie knew Mikey was often too lazy to remove and clean; who knew how long it’d been since they had been adjusted. His knee and elbow pads seemed to hug his joint more tightly too: Mikey was experiencing some sort of growth spurt.

When Mikey finished his ranting and stood up, Donnie noted that while Mikey usually only came up to his chest, he was nearly chin level with him now. Whether it was the closer passive proximity of their faces now or not, Donnie noted that Mikey’s jawline looked a bit more defined too, almost scruffy: masculine. Donnie only snapped back to reality when Mikey asked if Donnie wanted a soda from the fridge as he grabbed one though Donnie couldn’t help but notice a squeaky crack in Mikey’s voice: was Mikey going through a second puberty? Donnie figured it was possible, considering he was still far from understanding the extent that the mutagen had restructured each of their genetic codes, though Donnie only became more and more certain of that possibility as the weeks went on.

Steadily, not only did Mikey continue to inch taller and taller, but the hormones unleashing said growth spurt seemed to be prompting his frame to fill out too. Mikey’s scrawny musculature began to thicken, his biceps grew more defined, his triceps more vascular, and his shoulders wider by the day. His chest broadened, becoming barrel-like as a set of abdominals appeared where once a subtly bowing paunch had been, forming a distinct v-shaped torso. As his thighs grew meatier and his calves shapelier with muscle, Mikey’s voice deepened, doing away with the shrill, high-pitched squeal and replaced with a baritone gruff vocal character.

While Mikey was initially seemingly unaware of the changes, the day that he and Donnie saw eye to eye, something clicked in his head:

“Whoa…!” Mikey had exclaimed.

“Whoa is right,” Donnie had concurred as a smirk began to grow on Mikey’s face as he flexed his buffer arms and examined his bigger build. While Mikey was only just realizing the changes now, everyone else had long since clocked them, especially Raph. As he and Mikey had been hooping, Raph noticed that it was gradually getting harder to play bully-ball with Mikey. He just felt sturdier; stronger. A few times too Mikey reached high enough to almost block his shots; something was for sure up. That was when Raph noticed Mikey standing a bit taller and his shoulder spreading wider: Mikey was getting bigger, and fast!

After barely winning a game by one point two months back, Raph started to avoid his bro; his ego couldn’t take it. HE was supposed to be the beefy, strong bro, not Mikey! Raph had begun to double down in the gym, but his marginal gains paled in comparison to Mikey’s naturally bulking physique. While Raph struggled to boost his bench 1RM by 10 lbs, Mikey’s chest doubled in size, arms tripled, and voice dropped another register, all seemingly overnight. Raph could hear the deeper and deeper thud of Mikey’s footsteps lumbering down the halls outside his bedroom and while Raph avoided his bro, he saw from afar Mikey starting to duck through doorways; even Raph didn’t have to do that!

One day, just as Raph was beginning to realize that even Donnie didn’t have to duck through doorways at his towering height, and the implications of said observation began to dawn on him, he felt a shadow fall over him from behind. He could hear the deep thrum of a heavy chested breath and feel that hot hair washing DOWN over him from above. Raph slowly turned to see the smiling face of his enormous, 7’6” bro, thighs as thick as Raph's torso, biceps like boulders, and broad chest stretching from end to end of Raph’s periphery, blocking out the world behind him: just Mikey with a basketball under his arm, his enormous hands nearly circumventing the ball.

“Yo, Raph,” Mikey smirked. “I know it’s been a while, bro, but…” Mikey wrapped his free arm around Raph’s neck, pulling the red-banded turtle into his sweaty, meaty armpit. “… I think it’s finally time for our rematch…”

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Amazing commission by MutanTAIL featuring everyone's favorite beefy orange-banded turtle: Mikey!Bro <3