A/N: Gift for EnsoDancer for the TMNT Secret Santa on deviantArt. Merry Christmas!

Disclaimer: I do not own Teenage Mutant Ninja Turtles.

Empty Fish Tank

It was the stiffness in his back and shoulders that finally forced Donatello out of his peaceful slumber. He was acutely aware that he was sitting in a chair rather than lying in his bed as he attempted to peel open his sleep encrusted eyes. As the dim outline of his lab slowly came into focus, he carefully lifted his chin from his chest, bringing up an arm to wipe a line of drool from the corner of his mouth. But as he calmly looked around, he couldn't help but feel that something was wrong.

It wasn't a panicky sort of wrong. His heart beat was steady, and no ominous sounds or shadows crept from the far corners of the room or beyond. As far as he could tell, he had simply fallen asleep in the middle of working on a project, probably pushing himself into the long hours of the night. But no matter how he tried to ignore it, there was this constant nagging at the back of his mind of something not being quite right.

As he placed his hands on his desk and pushed himself onto his feet, he tried to clear away the fog of sleep, force his brain to pinpoint the cause of his unease. But as soon as his weight had completely left his seat, he felt his right leg give way beneath him, causing him to fall back into the metal chair. He bent over to massage the leg, trying to coax some life and strength back into it. Glancing up, however, he noticed a cane leaning up against his desk.

Reaching for it, he studied it curiously. He didn't recognize it, that was for sure, nor did he have any idea how it had gotten into his lab. But as he tried to think back to the night before, he found not only could he not recall where the cane had come from, he couldn't even remember what he had been working on so fiercely that he didn't have the strength to trudge back to his bed afterward.

Leaning his weight onto the cane for support, he again rose to his feet. Glancing down, nothing on his desk stood out to him. Really his laptop was the only clue, but it was powered down, much to his surprise. As he lifted his gaze, sweeping it across the room, he found nothing that triggered any memories of the night before. Hobbling unsteadily, he turned to look behind him. His eyes widened slightly in realization as they at last fell upon a giant, familiar glass tank.

Taking slow and careful steps, he made his way in front of the large container, watching the contents floating about in the sickly green liquid. Placing a hand on the glass, it all came rushing back to him.

Timothy.

He'd been furiously working on a cure - a retromutagen - to save Timothy. The Pulverizer, as the boy had liked to call himself, had been his responsibility, but rather than trying to protect him, he'd allowed the would-be superhero to act as bait. It was that decision that had ultimately claimed his humanity and, in turn, gripped Donatello's heart with guilt. But there was something else, and as he glanced up at the nearby wall, a photo hanging of him and April reminded him of what had become of her father.

His friend's life had come crashing down in an instant as, wanting nothing more than to protect his daughter, Mr. O'Neil had shielded her from the ooze raining from above. It had been an accident; Donatello and his brothers had been careless and allowed the mutagen canisters on board the rogue Kraang ship to spill out. But though Mr. O'Neil had made sure April was out of harm's way, he could not save himself. Now, he roamed the city, a grotesque mutant - part man, part bat.

He looked at the photo sadly for a moment before his gaze hardened. Gritting his teeth, he turned back to his desk, ignoring the odd feeling that refused to leave him alone.

"I've gotta finish it..." he muttered, giving himself a light push off of the glass of Timothy's jar as he stumbled back into his chair. Discarding the cane, he grabbed his laptop, pried it open, and hit the On button. As nothing happened, however, he frowned. Pressing it a bit more forcefully, he tried again, but the dark screen continued to stare back at him in defiance.

"Lousy piece of junk." Slamming it shut, he practically threw it onto his desk in disgust. Swiveling around in his chair, he scanned the lab for one of his many notebooks. But his attention was quickly distracted by an ever so faint green glow coming from across the room.

The mutagen. Of course. Pushing himself up, he hobbled over to the substance, picking up a beaker full of it on a nearby shelf. So what if he couldn't access any of his notes? Most of it was in his head anyway, so it wasn't like he was starting from scratch. Making his way back toward his desk, he carefully set the container on his examination table before gripping the table's surface and slowly bending over until he could reach the storage space underneath.

"Now where's that microscope?" he mumbled as he slid open the door to one of the built-in cabinets. He began searching haphazardly through the various odds and ends piled on the shelves inside. "I know it's here somewhere..."

"Donnie?"

He jumped as he felt a hand gently touch his shoulder and quickly looked up, startled.

"Leo!" he cried, grabbing on to the edge of the table for support, "I didn't hear you come in."

"Sorry. I didn't mean to startle you." Leonardo's tone and expression were sincere. "I was just coming to get you for dinner."

Donnie paused for a moment as his brain processed this bit of information, eyeing his brother dubiously.

"Dinner? It's morning, it's not time for dinner," he said matter-of-factly as he turned back around and again began rummaging through his storage cabinets. Breakfast maybe, but dinner? It seemed Leo hadn't fully woken up yet.

Without even a glance, he waved his older brother away. "I'm not hungry anyway. Go ahead and eat without me."

But Leo refused to leave. Instead he knelt down so that his face was even with his sibling's. Blue eyes watched him patiently as he continued his search for the microscope.

"It is time for dinner," he insisted gently, "You just dozed off in here for a short nap, that's all."

There was that uneasy feeling again. Donnie shoved it away, but as he faced his brother and opened his mouth to protest, he found himself cut off.

"Besides," said Leo, "I made a special treat for today - pizza gyoza."

At this Donatello finally pushed himself fully upright, a look of pure shock on his face. His eldest sibling was not exactly known for his cooking skills. Mikey had always been the chef amongst them, but even then his creations weren't always palatable. Their little family wasn't exactly filled with culinary genius, and Donnie would definitely put Leo toward the bottom of that list, with only Raph's consistently burnt food being less desirable.

"If you made it, then I definitely don't want it," he said bluntly.

To his surprise, his brother simply smiled at him, a short laugh escaping from his mouth. "Hey, I've gotten a lot better over the past few years. I'm telling you, this is the best batch yet."

Yet? Donnie tried to figure out what his sibling meant. He couldn't ever remember Leo even attempting pizza gyoza before. He supposed it was possible he'd been practicing at night while he was holed up in his lab, but somehow that just didn't feel right. Nothing about this felt right.

"I don't know why you even bothered," he said at last, "You should have just ordered it from Murakami-san if you wanted it so badly."

The change in Leonardo's face and posture was so stark and immediate he would have to have been blind to not notice. His brother's entire body stiffened, and his mouth now formed a tight, thin line as he stared at him silently as if choosing his next words very carefully.

At first Donatello thought that perhaps he had been too harsh on him. It wasn't like it was a bad thing to encourage him to have other hobbies. But the odd feeling was engulfing him now, wrapping itself around him like a spider cocooning a fly caught in it's web, and somehow he knew that wasn't the cause of Leo's change in behavior. Looking into his sibling's eyes only further proved this. It wasn't shock or wounded pride he found there. No, it was a look of deep and heavy sadness. Something had happened - something big - and Donatello could merely wait and hope for an explanation as to what it was.

At last Leonardo spoke, his voice soft but firm.

"Murakami-san died a long time ago. You know that, Donnie."

The younger turtle merely blinked in response, dumbfounded. His brother's face was serious. This was clearly no joke, and yet he found the news wasn't all that upsetting. In fact, as he turned the information over in his brain a few times, it felt strangely familiar. It was as if he really had known it to be true, but it wasn't until Leo had brought it up that he was able to remember it. It was disorienting, and he looked away, his gaze arbitrarily wandering around the room.

"Have you taken your pills yet?"

Donnie slowly turned his head back toward his sibling, a confused look clouding his eyes. "Pills?"

As Leonardo's body loosened up, he carefully reached out to him, lightly gripping the arm that wasn't using the table for support.

"Come on," he coaxed, gently tugging on his arm, "Let's go to the kitchen, and I'll get your pills ready for you."

But Donatello quickly jerked his arm away, a look of annoyance contorting his face. Leo's hands hovered around him anxiously as he stumbled backward into the examination table, but he shrugged his big brother off.

"I told you, I'm not hungry," he snapped, grasping the edge of the table so as to not completely fall over, "And I don't need any pain medication. My leg just hasn't woken up yet. Once it does, I'll be good as new. Now, if you'll excuse me, I need to get back to work. I have to perfect that retromutagen for Mr. O'Neil and Timothy."

"You finished the retromutagen over a century ago."

Donatello's body went rigid, his grip on the table beginning to shake. His eyes stared blankly at the ground in front of him, lost in a whirlwind of thoughts as Leo's blunt statement hung in the air.

Careful not to startle his brother, Leonardo reached out and softly laid a hand on the younger turtle's shoulder.

"Look around, Donnie," he gave his shoulder a light shake, "There's nothing in here to experiment with. I had to throw out all of your chemicals and a lot of your equipment because you almost hurt yourself, remember?"

The blank look still firmly in place, Donnie mechanically turned his gaze back up to his sibling. He'd thrown everything out? That couldn't be right. Everything was right out there in the open for both of them to see. Leo simply wasn't making any sense.

"But the mutagen," he murmured as he glanced toward the beaker he'd retrieved only moments ago, "and my computer..."

"Your old laptop has been broken for decades now." Leonardo's voice was calm, almost as if he were talking to a small child, but Donnie was too overwhelmed to notice. "You refused to let me get rid of it, even though it's practically ancient. It was the first laptop you ever made, and I figured you couldn't injure yourself with it so I let you keep it."

Donnie's eyes fell on the old computer and he could see that his brother was indeed right. It was not only dirty and unwieldy, it was also covered in cracks. It had clearly not worked in a very, very long time. But looking at it he could still see himself holding it in his hands for the very first time, a wide grin on his young face as he was filled to bursting with pride at his accomplishment. It wasn't until Leo began to speak again that he was yanked out of the vivid memory.

"And look closer at that jar, Donnie," he instructed, pointing to the beaker on the examination table. Donatello obediently did as he was told, turning around to stare at what he had believed to be mutagen.

"That's not mutagen. It's algae. From the old algae pools, remember?"

Slowly picking up the glass container, he stared at it in confusion. There was no doubt the fuzzy, green substance inside of it was algae. Why had he thought differently? Aside from the color, it looked nothing like the ooze that had given them new life so long ago. How had he made such a simple mistake?

Putting the beaker back down, he knew there was a piece of the puzzle that was still missing. The state of his old laptop and the lack of mutagen in his lab was clear, but something still felt wrong.

"And Timothy?" he asked quietly, glancing back to his brother after a short pause, "I finished the retromutagen, but he's still here." A glassy, distant look veiled his eyes. "Did I fail?"

Donatello barely made out the faintest of smiles on his brother's face as Leonardo gently took his arm and led him to the giant tank. He moved as if in a fog until at last he was directly in front of it.

A part of him didn't want to look. But he found he couldn't tear his gaze away as Leo pointed to the glass, and as he followed the direction his brother's finger was pointing, it was as if the veil obscuring his view had been lifted. His eyes widened in understanding as he gazed upon not a deformed mutant, but an old fish tank filled with murky water that clearly hadn't been cleaned in a very long time.

"You didn't fail," said Leo at last, giving his younger sibling's shoulder a comforting squeeze, "After we defeated the Kraang, you were able to cure him. He went back home to the family that had been looking for him for months. You decided to turn this old jar of his into a fish tank. You always said watching them had a way of calming you down."

The memories of the day Timothy was returned to his human form came rushing back to him as if he'd never forgotten. It seemed silly to think that he had. It was such a joyous occasion, and as Donnie had watched the human's tearful family reunion from a nearby rooftop, he had felt such a huge weight being lifted from his heart. To have suddenly forgotten that immense sense of relief was baffling and terrifying.

Glancing over to the wall, he looked more clearly at the photographs hanging there. A lot of them were yellowed with age, depicting scenes long since passed. A young, teenaged April stared back at him from some, but others showed a mature woman. But one in particular had caught his eye. It was a wedding photo, taken shortly after she and Casey had gotten married, and there standing proudly next to April was a fully human Mr. O'Neil. Timothy wasn't the only one he had cured.

Turning his attention back to the old fish tank, he placed his hand again on the glass, watching the bits of algae and muck drift around the grimy plastic plants that still remained. Where there used to be flashes of bright colors from the fish he had kept now was merely sickly, green water in desperate need of changing.

"Why is it empty?"

Donatello could feel his brother looking at him out of the corner of his eye, but he didn't want to return the gaze. He was afraid of what he might find there. There should have been no need for him to even ask. He should have known the reason. But his mind refused to supply him with an answer, instead practically suffocating him with a deep, dark void where his memories used to reside.

"All of the fish died," said Leo at last. But this response had been short, clipped, as if there were something more behind his words. The grip he still had on Donnie's shoulder tightened, but this was not the comforting squeeze from earlier. This was a sign of tension, of his brother holding something back. And though something nagged at him, telling him he didn't really want to know what it was, that curiosity of his got the better of him.

At last turning to look into his sibling's eyes, he asked, "How did they die?"

The sadness he found hidden in Leonardo's eyes was what he had expected to see, though he didn't know why. But his older brother quickly tried his best to steal his face and hide his emotions before answering.

"They died because you could never remember when to feed them," he said at last. "Sometimes you would feed them ten times in one day. I tried hiding the food, but then you'd either tear your lab apart looking for it or you'd forget all about it and not feed them for days." A sheepish smile tugged at the corners of his mouth. "Admittedly I wasn't too good at remembering either as I'd never taken care of fish before, so some of the blame is on me."

Donnie returned his gaze to the empty fish tank sadly. "That's right," he mumbled, "I couldn't take care of them anymore. I let them down."

He felt Leo's hand move to his shell, rubbing it in gentle, reassuring circles. "You didn't let them down," he said quietly, "Some things... some things are just harder to do when you're our age."

Leonardo suddenly straightened, clapping the back of Donatello's shell lightly. "But one thing we'll never be too old for is dinner," he said, raising his voice.

Donnie glanced over at his brother, finding a stiff smile plastered on his face. The sadness behind Leo's eyes had been masked slightly but still wasn't completely gone. But before he could give it much thought, he found himself being lead out of his lab.

"I worked really hard on this pizza gyoza, and I don't want it to get cold," the older turtle said as he slowly guided his brother out through the common area and toward the kitchen. He chatted nonchalantly as he helped him up the stairs, but Donatello wasn't really listening. Instead his senses were overwhelmed with the scent of cheese, tomatoes, and fatty pepperoni as it wafted through the air. By the time he was seated at the table, all he could hear was his stomach rumbling, reminding him of just how hungry he really was.

As he waited patiently for Leonardo to serve the food, he looked around curiously. His eldest sibling stood in front of the stove, but the rest of his family was no where in sight. The uneasy feeling was back in full force and now hung in the air like a cloud of thick smoke. While Raph being a bit late was no surprise, Mikey was always the first to the dinner table, his seemingly neverending stomach constantly begging to be filled. And Master Splinter was always on time, never missing a chance to eat with his sons.

Something was wrong. He couldn't put his finger on it, but something about this whole situation was off. It was both familiar and completely foreign. Despite his empty stomach, he suddenly lost his appetite, unable to even think about food while his mind scrambled to figure out what exactly was clawing at his brain, seeking attention. When Leo at last put a plate and glass of water down in front of him and took his seat across the table, Donnie opened his mouth to speak.

"Where is everyone?"

For some reason a part of him had expected his brother to lash out at him, though he wasn't quite sure why. So when Leonardo's shoulders slumped and the smile that had been on his face faded, he wasn't sure how to react. It was almost as if him asking the question out loud was something Leo had been both expecting and dreading.

His brother wouldn't look up from his plate as he answered.

"They aren't coming."

The older turtle's voice was quiet but firm. The statement hung in the air for a brief moment before Donnie pushed further.

"Why not?"

Leonardo at last looked up, locking his gaze with his younger brother.

"Because they're dead, Donnie. They died years ago. We're the only two left."

Donatello knew that the news should have been shocking. He should have been demanding an explanation, yelling at his sibling for keeping such an important thing secret from him. But as before, rather than horrified surprise he merely felt as if his eyes had been opened to something he'd always known. It wasn't that he was just realizing he'd lost the rest of his small family, he was merely just remembering it. Worse, he knew this wasn't the first time this had happened.

He couldn't tell if they'd been sitting there in silence for a few minutes or merely a few seconds, but at last he responded in a hushed tone.

"Oh. Yeah. You're right." He attempted a reassuring smile, though he was fairly certain it was entirely unconvincing. "My memory's not so good anymore."

Unable to hide his own sadness, Leo returned the pitiful smile, and as Donnie concentrated on his older brother's face, it was like he was seeing him as he really was for the first time that evening.

Wrinkles and deep creases lined Leonardo's forehead and crinkled around his eyes. His once bright green skin had paled over the years and now sagged ever so slightly. The muscle tone from his youth was replaced by a thinner frame, and there were scars from battles fought long ago etched into his arms and shell. His blue mask hung like a scarf around his neck, threadbare and faded. It was an image Donatello was very much used to, and yet it seemed like only moments ago his sibling's eyes had been young and full of the fire of life.

Breaking their eye contact, he fixed his gaze on his plate, trying in vain to mask the distress he felt over how easily he had forgotten his own family member's deaths. The reminder also had the unpleasant effect of forcing him to recall how each had died. Master Splinter had unsurprisingly been the first to go, peacefully in his sleep surrounded by his surrogate sons. Raphael had not been so lucky. He had been pushing himself to at least survey the city well into his 80s, and at last even with the extended life of a turtle his body had failed him. He had fallen to a simple mugger, dying alone in a sewer tunnel as he said his goodbyes through a vid screen. This had broken Michelangelo, who's smile never seemed to reach his once bright blue eyes afterwards. It was no secret that he had been closest to Raph, and it would only be a few years later that he would join him in eternal rest. Donatello had never pinpointed the exact cause, unable to bring himself to perform an autopsy on his baby brother.

"It's alright, Donnie," said Leo at last, jarring his younger sibling out of his distressing thoughts and back to the present. His voice was soft and comforting. "Why don't you take your pills."

It was an order, not a suggestion. Staring at his plate, Donnie noticed the two tiny, white pills next to his gyoza. It was his dementia medication. It was supposed to help him retain his memory, but it's effects had been weakening in the past few months. He knew a time where he would be beyond the medicine's help wasn't far off. For all the advancements in science and medicine in the last century, there were some illnesses that doctors and scientists were still blind to.

Without a word, Donatello did as he was told, picking up the pills and swallowing them with a small gulp of water. As soon as they'd gone down, Leo seemed to relax slightly, as if he thought they could magically heal him in an instant. He began eating his food and chatting about various things.

"I was thinking, we haven't had much company lately. It would be nice to see some friendly faces, don't you think? I was going to try getting ahold of Cody, seeing if he's available to come visit. I know he's pretty busy, but..."

But Donnie wasn't listening. He didn't want to admit that he had no idea who Cody was, so instead he concentrated on eating his pizza gyoza. His blank stare fell to his withered hand clutching the fork, no longer strong or dexterous enough to use chopsticks. Stabbing at one of the dumplings, he slowly brought it up to his mouth and took a bite.

Suddenly he was once again just fifteen years old. Seated inside Murakami-san's restaurant, his brothers at his side, he was openly gawking at the amazing combination of pizza and Japanese cuisine that sat in front of him. He had been unsure at first if he would enjoy the newly invented dish, but one bite had been all he'd needed. He and his brothers would gulp down the rest of them happily, wishing there were seconds.

A genuine smile crept across Donatello's face as he swallowed the delicious morsel with a satisfied moan. Using his fork to snatch up another one, he quickly popped it in his mouth, savoring the flavor. Licking the corners of his mouth, he looked back up at Leo who had at some point stopped talking and was now practically beaming with pride.

"Murakami-san is a genius," said Donnie, the corners of his eyes crinkling as his smile widened, "His pizza gyoza really is the best."

His brother's entire body stiffened, but he barely noticed as his head was slowly looking around the table, a curious expression on his face. Something felt off.

"Where is everyone?"

Something was nagging at the back of his mind, and as his questioning gaze returned to Leonardo, he couldn't help but wonder why his older brother looked so sad.

A/N: When I saw I had to write a story about Leo and Donnie, I had a mild panic attack. I tend to shy away from them for various reasons. I spent hours trying to come up with an idea before this one finally struck me. Not only was I happy to have finally thought of something, it was something I was excited to write. I really enjoyed writing this, so I'm glad I was pushed out of my comfort zone for once.

And as always, critics and grammar police appreciated! Thanks for reading!