Hi guys! Thanks for coming to read this little one shot I threw together. It's not my best work but I put lots of effort to it so I might as well show it.

The younger turtles are based off Kalaakaar-m8 AU on tumblr, you guys should totally check them out. Their art is great and cute and I love all their stuff.

One-shot summary: Donnie always preferred his space, but that never stopped his brothers from invading it. It always annoyed the heck out of him, and he assumed this time would be no different with Mikey...

Not the best summary but it's the basics of it.

Anyway hope you guys enjoy~ sorry for any grammar errors or just poor writing choices. I'm trying to get back in the writing groove.

But yeah! Thank you and Read on!

For Donnie, the day had started out normal; with him in his lair, burning time away on some tinkering per usual. It was normal for him to spend a lot of time cooped up in his lab, avoiding most social interaction like the tiny introvert that he was.

Earlier that day he'd found some peculiar objects in the trash heap he was frequent to visit, as well as some batteries someone had discarded. The batteries were dead- he'd confirmed after trying them on the TV remote- but he believed he could find a way to recharge them.

Despite being barely over 7, the little boy genius had the brain of an academic scholar, or at least the makings of one. Science and engineering was something that came natural to him, though he had no clue why. Each of his brothers had a special quirk, and this was his, no matter how "nerdy" it was (quote Leo).

Donatello was using a pair of makeshift pliers- which he'd constructed out of the handles of a pair of broken scissors, as well as carved wood- to twist two wires together. After doing so successfully, he carefully put down the assembled cross-wires, picked up his coffee mug, and took a sip of the dirty liquid.

Any adult would've reprimand him for drinking something like coffee at such a young age, but Donnatello got away with it. Even after his Dad had caught him with it once, he'd managed to get away with it. He wasn't sure if it was because his dad didn't care, or that he had thought it was dirt water. Either way, it meant the young genius could caffeinate in peace.

At least… most of the time-

"Donnie?"

The purple clad turtle caught the soft sound of someone calling his name, turning in his swivel chair to track its origin. He squinted as his eyes caught the drastic change in lighting of the world outside his lab. He'd forgotten he'd left the door open, which was a horrible mistake to make.

In a home with brothers like his, an open door was pretty much an invitation to waltz in as one pleased. On the other occasions he'd mistakenly left the door open, Leo was always an inevitable visitor, as well as Raph and on occasion: Mikey, if he was in a wandering mood (he always was).

Donatello hated the invasion of space, and hated even more the insistence of his brothers to touch everything they made eye contact with. It was an unneeded stress trip that he never enjoyed.

Though, despite how much he hated it, he still found himself forgetting to close the door on occasion, only to regret it over and over.

Now, the door was open again, and he couldn't help but let out a sigh as he looked to see who was barging in this time. Much to his surprise, however, the circular doorway was empty, no sign of any of his 3 brothers.

Donnie scanned the area with a raised eyebrow, utterly confused. He swore he'd heard his name, or was he just hearing things?...

After searching the dimly lit surrounding of his lair, he came out unsatisfied at finding no one. With a frown, the turtle slowly turned back around in his chair toward his desk. Except, when he expected to find only wires and various parts, he also found his smallest brother, sitting on his desk as if he'd been there the whole time.

Donnie jumped violently with a yelp, not expecting his younger brother's sudden apparation. The goggles hovering atop his head fell down over his eyes with the jostle, startling him even further. After also nearly falling out his chair, the purple clad turtle finally began to gather his bearings, sending a glare at his younger brother.

The youngest smiled, giggling softly at his lanky brother's reaction. Donnie swore the kid hid something under that innocent smile of his.

"Mikey! Don't do that!" He spat frustratingly, turning the makeshift goggles back upward, and only arousing more amusement from his brother.

"Sorry Donnie, didn' mean to." The orange turtle apologized, kicking his legs back and forth from where they were draped over the side of the desk.

Donnie just sighed, pinching the space between his eyes, feeling a headache coming on, "it's fine-" he muttered.

If it had been any of his other brothers he wouldn't had let it go so fast, but this was Mikey. Whether he wanted to admit it or not he had a soft spot for his younger brother, one that was more obvious than the ones he had for his other brothers at least.

The orange clad turtles smiled, turning his attention to the organized mess on Donnie's desk.

"What are you doing?" He asked innocently. Unlike Donnie, Mikey fit his age perfectly.

The boy genius scooted his chair forward, closer to his desk than it had been, readjusting the small lamp that was providing him work light, "just working on a project..." he muttered, acting as if he was ready to back to work and tune Mikey out.

Unsatisfied with such a bland reply, Mikey decided to take a closer look for himself. He rotated himself on the desk so his plastron sat against it's cold surface, then leaned his head down close to the experiment.

However, Mikey's idea of "close" was putting his face up millimeters away from the older brother's project, greatly interfering with Donnie's need for personal space.

"Mikey-" the purple clad turtle hissed, his annoyance tolerance quickly filling up to its maximum capacity.

The turtle in question paid no mind to Donnie's annoyed tone, pointing instead at the small battery that sat in the midst of some stray wires, "Is that a batter- bat...battie…?" The younger tried to ask, but found himself unable to recall the name of the small cylinder object.

"Batterie, and yes." Donatello finished for him, still feeling rather annoyed as he tried to forcibly move Mikey's head away, "now please move."

"I just wanna see!" Mikey whined, fighting back against Donnie's push. The small child had changed gears rather quickly, from his previous innocent demeanor to one of a whiny child.

"Mikey, cut it out!" Donnie retorted, his inner child also showing its colors. His bitterness towards his brother's lack of basic knowledge of personal space ticking him off, "you can't be that close!"

Instead of adhering to the logical compromise that was right in front of him, Michelangelo kept struggling against Donnie's ever growing force. He even started reaching out through the arms that were holding him back, as if he wasn't just fighting to simply look at the battery anymore.

This is the point where Donnie was once again beginning to really regret forgetting to close his door. What he thought was going to be a bearable arrangement- Mikey sitting on the desk a good enough ways away- had quickly proven to be far from such. Mikey was being a pain, and unfortunately for Donnie, it was only gonna get worse.

Without warning, Mikey gaped open his mouth and chomped down on the hand draped over his face. In a fit of sudden pain, Donatello drew back, clutching the bit hand and staring at it with disgust. 'Did he just bite me?' His thoughts rang with a mix of anger and shock, manifesting in a very sudden urge to want to clobber his brother over the head.

However, before the scientist could even think to yell at his little brother, the younger was scrambling a crossed the table, now free from his brother's grasp.

Mikey had gotten to the work space on his knees, quickly picking up the barren battery without so much a second thought. Donnie wasn't sure if Mikey even knew why he wanted to hold it, but he presumed his little brother's hyperactive brain had jumped the extra step for him in that moment.

The tot, turned proudly, battery grasped in one of his tiny hands, which was almost completely hidden under the bagginess of his hand-me-down hoodie sleeves. He had a big victorious grin on his face, as he won a battle- though none had been declared. He was ready to examine his well earned prize, however, as the young turtle turned, one of his legs lost support of the desks surface, sliding off before the child could even begin to catch himself.

"Mikey!"

Donnie watched the disaster start in horror, forgetting his frustration and anger and immediately rushing forward. In his haste, he nearly tripped, arms outstretched to catch his younger brother. In a swift movement, he turned on a heel, catching the small turtle on his plastron.

Unfortunately, the force caused him to completely lose his footing, and he tumbled backward with Mikey in hold.

His shell hit the edge of his chair, moving the seat away briskly on it's wheeled feet, and leaving him to make his second landing harshly on the ground.

The purple clad turtle laid flat on the ground, trying to catch his breath, but it was hard with Mikey still sitting on top of his chest. The younger hadn't seemed to have processed what had just happened yet, and it took a while for his wandering gaze to fall upon his older brother. He didn't say anything, and Donnie couldn't really tell what the young turtle was feeling; it didn't help that he had a distorted floor-view perspective though on the matter.

The older began to make his way into a sitting position, feeling a soft ache pulse in his shell as he did. It was a setback he hated most about being a soft shell; having such an open part of you be so fragile you couldn't even bump it without it protesting profusely, was inconvenient.

He brushed off the light pain, watching as Mikey fell into his lap in turn with his own upright movement. Both of them sat on the floor, a bit disoriented from the whole ordeal.

This is why he should close the door...

Donnie rubbed his temple, the pulsing in his head only getting worse now. He squinted down at his little brother, who was looking down at the floor and hiding his face.

"Mikey..." he said quietly, and with the same edge of annoyance he'd been feeling since his brother entered the lab.

His little brother tensed at the sound of his name, turning more so his legs draped over Donnie's knees.

"I'm… I'm sorry…" he muttered bringing his hoodie-covered hands up to his face.

Donnie heaved another sigh, rubbing his fragile shell where he could reach. He could hear the guilt in his little brother's voice, but he still couldn't help but feel aggravated. The small turtle was far too hyper at times, and of course he had to be it inside the one place he'd rather have him out of in the first place.

"It's-"

He wanted to say it was fine, the sooner to rush the small turtle out of his lab and close that door (which was still mockingly open), the better. However, that's not what came out. Whether from his conscious or some out-of-body source, Donnie said something that contradicted everything he was feeling.

"You okay?"

The words shocked him, not sounding like his usual apathetic self. Nonetheless, it's what had come out, and he decided to roll with it.

He peered down through the hood that was hiding the tot's round face, hoping to receive an answer to the question he honestly assumed he knew the answer to already.

Mikey looked up at him with those big blue orbs they called his eyes. Looking at him like this, the lanky brother could see tears surfacing in the corners of them ocean colored balls. After a moment of staring, the younger looked down and gave a soft nod, then spoke with a voice just above a whisper.

"I... just wanted to see you make cool stuff like you always do...I'm… im sorry I messed up your exp… expri… espies…" the orange turtle's voice was weary as he attempted to say the ambitious word he'd only heard Donnie say a couple of times before.

Donnie blinked, taken aback by his brother's statement. He didn't expect that his younger brother would be interested in his tinkering… or that he even thought it was cool.

"Experiment…" Donnie finished for his brother once again, still pondering over the statement. He'd always jumped into being aggravated when his siblings entered his lab, assuming they were only there to cause mischief. While Mikey hadn't avoided such, his motives for being here were different. The young tot wanted to see him make something- he thought the stuff he made was cool. Not nerdy, but cool.

Donnie let a small smile escape him, feeling something he wasn't used to feeling. Gaining 'Ooos' or 'Awes' wasn't something Donatello necessarily expected from his family. He wasn't exactly torn up about it, he never really built things for approval. When he did make things for his brothers, they were usually too caught up in the complexity to appreciate what he had built. It always took a few levels of "dumbing it down" for his brothers to even understand what it did. Understandable, they were kids, but despite their age, Donatello's vocabulary far exceeded any of his brothers.

Thus, his inventions were dubbed nerdy, too sciencey, or even so simplistic they lost their original purpose. In addition, no one really seemed to care about the process that went into each invention. They were much more interested in the product, if anything.

That's why it surprised Donatello what his brother had just said. The small turtle wanted to see him work, he found something cool about the things he built.

With that new information processed, Donnie's mood suddenly changed. Hearing Mikey's words made him feel a sense of pride he never knew he was missing. It felt nice, wonderful in fact, to hear those words from his little brother of all turtles.

He placed a reassuring hand on the younger's head, drawing the youngers attention back to him, "if I'm being honest… you probably didn't mess up anything. I hadn't really connected the battery to anything yet…"

At mention of the battery, Mikey looked down at the small cylinder in his hand. With a small smile, he grabbed Donnie's free hand, surprising the inventor, and placed it palm-side up in front of him. The boy genius watched as his younger brother then placed the battery in his hand, helping enclose his fingers around it.

Donnie looked down at his brother, not knowing whether to laugh or roll his eyes. Mikey simply stared back with a smile he was most likely hoping would make up for everything that had happened.

In all honesty, it shouldn't have. Mikey had waltzed in uninvited, demanded to get in his personal space, had the gall to bite him, and then nearly hurt himself by falling off the desk. Donnie should've been angry for any one of those reasons, but he wasn't, he didn't know why, but he wasn't. Maybe all that "Jupiter Jim" binging was rotting his brain.

Whatever the reason, didn't matter, because he didn't feel any resolve to get mad at this point. He rubbed his little brother's skull with the hand he still had placed there, the action arousing a giggle out of the young turtle, making his grin wider.

He'd let it go this once...

"Thanks Mikey…" Donnie muttered softly, his gaze less directed towards his brother, and more to his own crossed legs.

The orange clad turtle stopped giggling to look up at his brother curiously, "For what?" He asked.

Donnie hesitated for a moment, before continuing, "For… thinking my stuff is cool…"

The tot stared up at his brother, the confused look on his face turning back into his signature smile.

"You're welcome!" He said proudly and with gusto.

Donnie let out a small laugh, shifting his weight to his legs as he did so. He pushed himself up into a stand, deciding he'd been sitting long enough. He had Mikey cradled in the hook on his left arm, supporting him with his other.

He placed the cylindrical battery that was still in his hand back onto the desk, making sure it wouldn't roll away. Then, he took one last look at the parts he had been in the process of arranging just a little while ago, remembering how eager he'd been to get back to it before. Now, he didn't feel much like simply going back to his mindless tinkering.

He looked back at his brother, who was barely only a year younger than him, and yet so small. The young turtle stared back, pressing his lips into a smile that warmed Donnie's big-brother heart.

He then proceeded to clear his throat, trying to pick his next words carefully, "Would you wanna… watch some Jupiter Jim?" He mustered out, rubbing the back of his neck with his less occupied hand.

His baby brother's face lit up in an instant, and the tot nodded his head so fast Donnie thought he was gonna get whiplash.

"Woah, okay okay-" The purple clad turtle said as he calmed down his hyperactive brother, "I'll take that as a yes." He continued with a smirk.

Mikey nodded again, this much more calm-like, but still full of eagerness.

Donnie smiled, turning his back to his desk and heading toward the open door.

As they made their way out into the, brightly lit space that connected all their rooms, Donnie took one last look at the open doorway. He pondered back on the past mishaps that came when he left that door open, and then this time. The thought came to him, and he didn't find himself arguing with it. Despite everything he'd felt before, despite how much he'd claimed to hate it, despite how much trouble it caused him. Despite everything, the thought prevailed...

Maybe the door didn't always have to stay closed.