So, this is an idea that's been rattling around my brain for a long while. There are so many different crossovers you can do with TMNT, given that NYC is so often a setting for different series, and that the TMNT cannon allows for aliens, magic, alternate dimensions, you name it! So, I decided to run with it.

For context, the TMNT side of this is placed within the 2003 cartoon, right after the "Good Genes" arc and before the "Ninja Tribunal" arc – as if there were several months between Don getting well and the turtles being pulled into the NT season. The Godzilla: The Series universe is a little more complicated. I have been given permission by the awesome author Macx to use the "Deep Water" universe, but I have decided to eliminate the OC, Jeff O'Neal, to keep things simpler. If you haven't read "Deep Water" or "Gambit" or all the one-shots in between, you should! But what you really need to know to understand this story will be made clear as we go.

I don't own either TMNT or Godzilla – they are the property of corporations with big scary lawyers and I'm just me. But I am borrowing them for the purpose of entertainment. No disrespect is intended, and no profit is gained.

Enjoy!


It was a well-established fact that any time the phrase "like a moth to a flame" could be applied to Donatello, trouble was not far behind. Certainly all four of the ninja brothers had their interests, things that drew them and piqued their curiosity. But somehow Leo's fascination with Bushido, Mikey's video games, and even Raphael's unending search for freedom just never matched up to the chaos of Donnie's own pursuits. The "brainiac" turtle never sought anything that was obviously harmful to his family, of course, but he did investigate the unusual, the challenging, and the complicated, and these things, combined with technology and the turtles' famous luck, always spelled disaster.

In this instance, however, it was only a surprise that Donatello had held off so long.

"For the last time, Don, it's too dangerous!" Leo crossed his arms and glared.

"First of all, I know the risks. Second of all, I don't intend to get anywhere near him. And third of all, the possible benefits far outweigh the danger," Donnie stated calmly, not budging an inch before his elder brother. Beneath the logic and reason of his argument, however, the purple-clad turtle was tingling with scientific interest. How could Leo deny him the right to study perhaps the most important mutant in the world and the closest thing the turtles had to an ancestor besides Leatherhead? Not to mention a shot at deepening their knowledge of their own DNA?

"You've only been well for a little while, though. Are you sure you're up to something like this?"

"Of course I am, Leo. Even Leatherhead and Master Splinter cleared me for training again."

"Then you won't mind if we come with you," the leader of the brothers replied.

"Yes, I do mind. Do you remember the last time I trusted you guys with any of my equipment? Or even trusted you just to stay out of my way while I handled it?"

"Dude, that was totally not my fault!" came a petulant voice from across the room. "When are you gonna let that go?"

"When you prove you're not a doofus," Raphael put in, helpfully bopping Mikey on his domed head.

"My point exactly," Donatello said, meeting Leonardo's eyes again. "You don't want me doing this more than once, and the only way to cut down the number of excursions is to make sure I get everything I need on the first try. Without anyone helpfully breaking any of my instruments."

"What about April, then? At least you'd have some backup in case anything went wrong, and she wouldn't mess up your gadgets."

"She's taking Casey to visit her family, and you know it."

"Do you have any idea what will happen to you if you're seen? Or, shell, Donnie, caught in the crossfire?"

"Which part of 'ninja' are you not taking into account here?" Donatello countered a bit sharply.

"Drop it Leo," Raph advised, coming to stand beside the other middle turtle. "You're not gonna win this one."

Donatello smiled at him thankfully. He shouldn't have been surprised. After all, if any of the others could understand the thrill of the risk that made this trip more than a scientific outing, it would be Raphael. Besides, he had a sneaking suspicion that his own fascination with the subject was somewhat shared by his red-clad, rebellious brother.

"There's nothing I can say that will convince you?" the eldest turtle sighed in resignation.

"Not really. Sorry Leo." Shouldering his bag, Donatello finally walked past the obstacle that had kept him in the lair the last fifteen minutes, feeling excitement starting to bounce in his step. "I'll be back soon."

Mikey looked up from his movie marathon for a moment, before yelling at his retreating brother, "Say hi to Godzilla for me!"

--==OOO==--

Though each of the turtles knew New York City backwards and forwards, not only the streets but the sewers and the rooftops, there were areas they just didn't frequent. Some, like Times Square, were due to the sheer number of people around – not a good thing for mutants trying to lie low. Some, like the quiet brownstone districts that were purely residential, held no interest for them. And some, like Staten Island, they avoided for other reasons.

An ear-splitting roar thundered through the air as Donatello threw himself nimbly behind some crates to take shelter in the long shadows of dusk. But no amount of ninja training could prevent the gasp of wonder that escaped him as something enormous rose up from the water only half a mile away.

Godzilla was beautiful. Perhaps not to the un-scientifically minded – Mikey had declared him the world's ugliest creature except for Raphael – but to one purple-banded mutant turtle, he was the pinnacle of what science, evolution, and the magic of chance could create. Shaped more like the T-Rex of prehistoric times than any modern lizard, Godzilla was an improvement upon the dinosaurs in every way. His forelegs were strong and flexible, almost like human arms; he could move easily at varying speeds including a blinding-fast sprint; he breathed a type of radioactive fire like a dragon or wyvern; and yet he was intelligent and self-aware, too. Of course, very few humans believed as much – the very few who spoke of him even vaguely complimentarily mostly considered him a nuisance until some monstrous thing appeared that needed a massive exterminator. But Donatello had been studying him long enough from afar to see much that the public would never know of their hometown miracle.

"Wow," the turtle breathed, craning his neck to take Godzilla in from head to toe. Though they lived in the same city, none of the turtles had ever been this close to Godzilla before. Partly it was through Leo's caution; as leader, it was his job to make sure none of his brothers got eaten or fried by giant lizards. And partly it was because, as mutations themselves, the brothers had never wanted to risk exposure by getting close to something so obvious, something regularly dogged by military copters, official personnel, and the press. But today was different.

"I'm so glad I found that network," Don smiled to himself, his mind glorying in discovery while he took dozens of photos, distance-readings and a dozen other measurements on his equipment. A week ago, while researching Godzilla, the genius had stumbled onto the merest whiff in cyberspace of a secured network within his search parameters, and after a day or so of intense hacking against some extremely impressive security, he had broken into a veritable treasure-trove of information. Definitely a first-rate computer whiz, even if they did have an odd sense of humor, given some of the warnings he'd encountered and ignored. Whoever was keeping these notes had intimate knowledge of the beast, his chemistry, his habits, and most importantly, his lair. Armed with this, the turtle knew he could approach a secluded area away from the usual entourage of attention and observe Godzilla safely, and thus his study began.

"If I can just get enough data on Godzilla, maybe I can use it the next time something happens to one of us," Donatello muttered as he switched gadgets while keeping an eye on his quarry. "I'm sure there's something I can learn from his biology that I could apply to our genetic makeup. But to do that, I think I need a sample."

The turtle took about 45 seconds to think over the lecture he would get from Leonardo if his brother ever found out what he intended to do. Even worse if Master Splinter found out. But Donatello was determined. After the very recent outbreak virus had caused him to mutate into something primal, carnal, mindless, it had shown both Donnie and Leatherhead that they simple did not know enough about their own DNA. The one thing Donatello would give anything to prevent was a repeat of that scenario – they might not be so lucky in finding a cure next time, and they certainly were not about to go back to Agent Bishop for it. He swallowed the familiar lump of guilt for what he had put his family through for his sake. So, if the risk meant a chance that could win him the knowledge to save his brothers if such a thing ever happened again, he was willing to do just about anything to take it.

Carefully and precisely, Donatello stowed all of his equipment in his bag, each in its very particular place for maximum efficiency and protection against damage should the bag be shaken around in the course of movement, leaving only one in his hands. It was a little metal thing about the size of the cardboard tube inside a roll of paper-towels, but it was one of his niftiest gadgets yet. By flicking a button, it extended to a narrow, tapering 20-foot pole with a sharp metal piece on the end. Hopefully he could just use it to swipe some skin samples from where Godzilla had been instead of actually getting in range of the creature, but if worse came to worst, at least this would give him a fraction of a margin for error.

"All right, here we go," Donnie breathed as he moved silently from his hiding place towards where the massive creature stood. It appeared that Godzilla had exited the water near an old dock of some kind and was rooting around the area. As the turtle approached, he could hear the telltale mumble of conversation, so he quickly switched tactics and took to the rooftops. Drawing as near as he dared, Donnie flattened himself on a building overlooking the dock area and peeked over the edge, listening intensely.

"It looks like he's healing up fine after that last encounter," came the voice of a woman with long, fiery red hair. She was standing disturbingly close to Godzilla, shining a bright flashlight on a portion of scales on one leg that had definitely been recently burned. "Do you think you can get him to let you examine his eye?"

"I'll try," answered a young man, the one Donatello recognized from the news as Dr Nick Tatopoulos, something of an expert on certain types of mutations. To Donatello's astonishment, the doctor stepped even closer to Godzilla, speaking more than shouting, "Come on down, big guy." His voice was even, confident, and almost coaxing, in spite of speaking barely loudly enough to be heard several stories up.

Snuffling a puff of air that could send a helicopter off-course, the mutant slowly lowered his head, his whole body curling into a crouch just yards from Dr Tatopoulos. And when the man laid an expert hand on his enormous snout, Godzilla let out a soft wuffling noise that was almost a purr. Donnie's eyes went wide at the incredible degree of comfort this man had with one of the most aggressive, dangerous, territorial creatures on earth.

"All right, just let me take a look, Godzilla." His voice was still that steady tone, even as he used some of Godzilla's jaw-ridges to climb halfway up his head. "Looks like it's healing okay, Elsie. Hand me that disinfectant."

The redhead took hold of a gallon jug with a spray-nozzle fastened on the front and cautiously approached. However, she stopped as soon as Godzilla's bright eye opened and turned fully on her.

"Um, why don't you come get it?"

"Elsie, he won't hurt you," Dr Tatopoulos said chidingly as he jumped easily from his perch to take the jug from her.

"Let's just call it me being respectful of his personal space," she replied.

"Hey guys!" came a new voice. Donatello looked for its source but from his position could not see where it was coming from. "We got something coming across from the insurance company. Come check it out!"

Perplexing as those words were, the turtle was even more confused when both individuals below moved rapidly towards a ferry-building at the water's edge without hesitation. Godzilla raised his head seemingly questioningly, then lumbered almost gracefully to his feet. A few moments after the humans were out of sight, Donatello saw the giant creature swing his head around, as though searching the area. Then his breath froze and caught in his stomach.

Godzilla was staring at him.

Every impulse in Donatello's body was suddenly torn in half between bolting at top speed and shrinking into his shell. But everything in the turtle's mind was saying something else, and after a tortuous few moments of waiting to be incinerated, he trusted those instincts instead. Very, very slowly, he got to his feet, making no sudden moves and keeping his body as relaxed as possible.

"He didn't hurt those people, and he won't hurt me," he told himself firmly, hoping it to be true. When he was standing at his full height, he waited.

Godzilla, eyes locked intently on him, took a few steps forward until he was close enough that Donatello could almost feel the moisture still dripping steadily from his recent emersion in the ocean. Hot breath washed over his face, but the turtle stood still. All his knowledge told him that Godzilla was a predator, and if he ran, he would look like prey. "Besides," he thought ruefully, "I could never run fast enough anyway."

Donatello lifted his head a little more and met Godzilla's gaze. There was something in the bright eyes of the creature that stirred the ninja's heart. It was like when the turtles had first encountered Leatherhead – a sense of kindred belonging. Removed as he was, Godzilla was as near a relation as they would ever find on earth, and he was, perhaps, the best of them all.

Donnie was so lost in his amazement that he never heard the step ascending the rooftop behind him, never heard the tiny sound of a gun cartridge clicking into place. He only felt the sudden, sharp prick of a dart on his arm. Turning in alarm, adrenaline fighting the force of a powerful sedative, he saw a figure moving towards him. Donatello drew his bo, but the drug working through his system made him slow and awkward. Another dart struck near the first and he crumpled.

The last thing he saw before enforced darkness crept over him was a glowing, intense eye.

--==OOO==--

"Dude, chill out!" Michelangelo advised. "I'm getting tired watching you pace like that."

"Something's not right. Donnie said he'd be back soon, he's not answering his Shell Cell, and it's been hours."

"He's probably just caught up in the geek-dom of seeing Godzilla up close," Raphael commented, shrugging. But Leo noticed his brother turn back to the punching bag and smack it tensely; apparently, he wasn't the only one who was worried.

"No. Something's happened. I can feel it. We need to check it out," Leonardo decided, the twisting in his stomach only getting worse with every passing minute. He had learned long ago to trust his instincts when it came to his family, and right now, they were telling him his brother needed help.

"I agree," came the serene voice of Master Splinter. "Donatello would never leave us in such worry for so long, especially after recent events. Go and find him, my sons. And come back safely, all of you."

"If you say so!" Mikey grinned, bouncing off the couch and joining the other two. "It's not like I'm going to pass up the chance to see the G-Man up close!"

"If that's what it takes, then all right," Leo agreed, leading the way out of the lair. "I'm just hoping that isn't what got Don in trouble in the first place."

As they made their way out of the lair and towards the Battleshell, Michelangelo chewed on the inside of his cheek nervously when his brothers weren't looking. In spite of his laughing words, he was worried. He hadn't really thought about it before, but maybe Leo had been right. Maybe letting Donatello go alone to see Godzilla had been a bad idea. Would he have had the chance to call for help if he needed it? What did giant mutant lizards eat anyways? Hopefully not turtles. Mikey's stomach turned. Maybe Don was just late. That had to be it. Anything else was more than he wanted to consider.

--==OOO==--

"I've never seen anything like it," Nick said admiringly as he looked over the prone body. "It's definitely a mutation, but unlike anything we've ever encountered."

"What do you mean?" Mendel Craven was busily rooting through the tote-bag that had been on their visitor, taking inventory of everything he found. "What makes this one different other than the luggage? Although generally we don't see them sized like this – usually they're either microscopic or giant."

"Though much smaller than most of the ordinary mutations we have…dealt with, how many of them have carried weaponry?" Monique asked pointedly. She had refused to stand down even after being assured that the creature could not possibly break the restraints, training her tranquilizer gun on it expertly. The mutant's staff weapon was behind her, and she stole an appraising glance at it again. Well-used and perfectly balanced, and what she had seen of the creature's stance before the powerful dart had forced it into unconsciousness had belied training, knowledge, and thinking. In other words, a supremely dangerous possibility.

"Isn't 'ordinary mutant' an oxymoron, kinda like 'jumbo shrimp' or 'military intelligence?" Randy asked. At the withering look from Monique and a muttered comment about "moron indeed," he shrugged, then went back to the laptop that had been in the bag. Somebody had hacker-proofed it but good.

"Some first-rate equipment here," Elsie said, looking over Mendel's shoulder. "Some of this stuff is on par with ours, even if it's built a little differently."

"How so?" Nick asked.

"Well, take this, for example," Mendel waved a gadget. "We have one just like it, but the keypad on this one is much bigger and wider than ours."

"Built for thicker fingers," Nick nodded, pointing at the mutant's hands.

"Are you telling us this thing built equipment better than Mendel's?" Randy asked.

"I said it was like ours, not better!"

"Whatever."

"Cowabunga!"

"Cowa-what?" Mendel squawked, looking at his prized piece of robotics equipment, whose head was now rollicking back and forth as it finished computing. "Randy, what did you do this time?"

"I didn't do anything! Can I help it if NIGEL is continuing his eternal search to find some personality? He certainly won't get any from you!" he hacker retorted.

"Leaving that aside, what did NIGEL find?" Elsie interrupted the old argument. While Mendel fumed, Nick bent over the analytical screen.

"According to this, we've got a male mutant terrapin on our hands, created not by nuclear radiation, but something else." Nick felt himself growing more and more interested with everything he read and saw – whatever this was, this turtle was no mindless beast. In fact, it was intriguingly human. And if the figures in front of him were to be believed, possibly quite intelligent.

A moan brought all five individuals from their various activities to the creature bound in their midst.

"It's coming around," Monique said, waving the others back and readying her weapon. While Mendel and Randy obeyed and Elsie threw the Frenchwoman a glare, Nick ignored her completely and stepped forward.

"Wha…what happened?"

Nick gulped his surprise as he met a pair of knowing, albeit foggy eyes. This was definitely the first mutation they'd met who could communicate verbally. As the turtle appeared to shepherd its wits back into order, he leaned over it cautiously.

"You were tranquilized," he said hesitantly. "You're in our lab."

The turtle looked around, his mind obviously clearing as the last chemicals in the dart faded from his system. Experimentally, he tried to raise a hand, only to find it bound.

"Why am I tied down?"

There was real fear in the question, and Elsie found herself moving forward. Without knowing she was going to do it, she took the turtle's left hand. It was tense, calloused, but it gripped hers like a lifeline. Her heart warmed to the creature instinctively. There was something in its face, something expressive. If the face had been human, she'd almost have called it gentle.

"You're all right. We're not going to hurt you."

"Yeah, I've heard that before. Look, Dr Tatopoulos, I know mutations are your specialty, and I'm sure I'm a fascinating subject of study, but I'd really like to make it clear that I am not a lab rat. I'm a sentient being, and I'd like some say in my circumstances. My name is Donatello, and I'd appreciate not being in restraints, please. If you are willing to let me up, I'm sure there's plenty we can learn from each other on more equal footing." The beginnings of an idea was blossoming in his mind, the solution to a problem he hadn't quite defined, but it would be difficult to implement while not viewed as an equal. And while tied down. Definitely more difficult if he became a specimen.

The HEAT team exchanged glances. As Randy would have said, it was sort of a new level on the weirdness-scale: a talking mutant terrapin who was obviously intelligent, self-aware, knew at least one of their names, and had the clarity of mind to make a polite request. Nick was halfway to unbuckling one of the binding straps when a hand slapped his from the table.

"Non. We do not know how dangerous it is," Monique said crisply.

"Oh, come on! How many mutants have been shorter than us AND able to talk before they breathe fire and destroy everything in sight?" Randy asked. Then, thinking over his words, "Maybe that wasn't as helpful as I intended."

"NIGEL says the terrapin doesn't have much in the way of a radioactive signature. So no breathing fire on this one," Mendel reported. "And if you ask me, it doesn't seem nice to keep somebody tied up when they're…sort of a guest. On the other hand, that whole 'destroy everything in sight' problem is not insignificant."

"It is not a guest," Monique argued. "It is a threat until we know otherwise."

"Donatello, you said your name was?" Nick asked. At the turtle's nod, he continued, "why were you sneaking around our lab this evening?"

"I didn't mean any harm," was the response, and to Elsie it sounded almost chagrined. Like a teenager caught out after curfew. "I only came because I was trying to study Godzilla, get some readings on him. It is vital to my research that I acquire as much knowledge as I can about mutations and the way their molecular structure and DNA can be impacted."

"Oh, yeah, that sounds real threatening," the paleontologist rolled her eyes.

"I know you deal with things that mostly just want to eat or smash you, but I'm not like that. I'm not an animal, not a monster. I don't know what I need to say to convince you, but I really, really think you should trust me."

"Why's that?" Mendel asked curiously.

Donatello closed his eyes. Somehow, he felt relatively certain that "because if you don't let me up so I can check in at home, my brothers will come find me and make you trust us even less while they tear the place apart and kick the snot out of everybody to rescue me" was not the best answer ever. And it was, Donnie knew, a greater and greater possibility every passing moment.

The argument went round after round, Monique insisting on keeping him tied up and the others cautiously or enthusiastically advocating for his release, but with a sinking heart Donatello felt sure the question would resolve itself some other way. He heard them before anyone else – he had been listening for them his whole life. But only a fraction of a heartbeat after the purple-clad turtle was aware of his brothers' proximity, a rapid beeping went off from a computer terminal at one side of the room, and Monique turned towards the sound.

"Intruders." Loading the tranquilizer gun with swift efficiency, she gestured to Dr Tatopoulous. "I will handle them. See that you leave it there and keep it confined."

"No! You're making a big mistake!" Donnie said, desperately. The last thing he wanted was a fight between a scientist who was friends with Godzilla and his family. However it ended, it could not be a good thing. "Look, they're coming after me. If you just let me up…"

But it was too late.

The room plunged into sudden darkness.