A/N: Thanks once again to all my awesome reviewers, and most especially to InsaneDutchGirl and ChloeTheCriticCat who always leave such amazingly detailed reviews. You are so encouraging! So without further ado, please enjoy the end of the story!

Final Chapter:

Placing one arm under Donnie's knees, and one behind his back, Leo lifted him gently in his strong arms and carried him toward the computer system he had indicated, not far away.

"What's wrong, Donnie?" he asked, his voice laced with concern. "Why can't you walk?"

"My ankle's broken," Donnie mumbled through clenched teeth, clinging to Leo's neck and wincing as his brother unwittingly jostled the injury in question.

They had reached the high-tech piece of machinery and Leo kicked a large wooden crate in front of it for Donnie to sit on. Carefully, he lowered his brother onto it.

Reaching out a hand to steady himself against the console, Donatello tried not to allow Leo to notice how much he was still trembling. His brother could worry about him later. Right now they had a mission to complete.

"Let me take a look at that," Leonardo said, kneeling down and reaching toward Donnie's injured leg.

"No!" said Donnie firmly. "We don't have time. We have to stop the Kraang!" And he quickly explained to Leo what he knew of the Kraang's plan.

Leo looked over at the massive ship. "So, we need to destroy that before it takes off?"

Donnie nodded.

"And what are you doing?" Leo waved a hand in the direction of the computer Donnie was sitting at.

"I'm going to hack into the Kraang's system and corrupt all the files on 'Mutagen Five' so they won't be able to recreate it. Now, go!" He shoved Leo in the direction of the battle taking place between their brothers and the Kraang, almost directly beneath the ship.

"You sure you'll be OK?" Leo asked with big-brother concern, observing Donnie's pale face and shaking limbs. He knew he had a duty to perform, but his brothers' well-being took precedence in his mind. Every single time.

"I'll be fine. Raph and Mikey need you!"

Not satisfied, Leo leaned down to retrieve a laser gun from one of the fallen robots nearby. He handed it to Donnie, saying, "Just in case any Kraang try to give you trouble while I'm not around."

Donnie smiled. "Thanks!"

Leo turned to rejoin his brothers, but Donnie called after him once more.

"Oh, Leo! I almost forgot. You should know, the Blue Goo is highly combustible."

Leo smiled. "Excellent." Then he turned, leaving Donatello at the machine to do what he did best.

As the blue-banded ninja raced to join the fight, he could see Raph and Mikey battling several Kraang bots at once. Both seemed to be enjoying the battle, grinning through their adrenaline rush as they swung their weapons at bot after bot, taking their revenge on the alien scum who had dared to hurt their brother. They were standing back to back, each protecting the other, and Leo was pleased to see how quickly they had adapted their fighting style to compensate for their new vulnerability.

Leo kept an eye on his brothers as he leaped over a control panel and sliced through two Kraang droids on his way to reach them. He saw Mikey take out a robot with his nunchuks, then, to Leo's alarm, the orange-banded ninja suddenly stumbled and fell to his knees. Leo was too far away to do anything yet, but he heard Mikey cry out, "Raph! My leg's asleep!"

Instantly Raph was standing over his brother, slicing up a robot that would have otherwise taken advantage of Mikey's momentary disability. A moment later, Mikey said, "OK, it's good now!" Raph helped his brother to his feet with one hand, while stabbing the face of a droid with the other. Leo watched this exchange with brotherly pride. Perhaps they could learn to fight as humans, after all.

By this time Leo had come up alongside his brothers.

"Leo!" called Raph, kicking one of the aliens clean out of its robot body. "Where's Donnie?"

"He's hacking into the Kraang's computer system."

Raph grinned. "Of course he is."

"No sign of the Blue Goo, yet, though," Mikey informed Leo as he snatched a laser gun from a fallen droid and used the weapon to blow up the head of another.

"I know." Leo's blades sliced a droid in two and the brain went squealing away across the floor. "It's in the ship." He pointed to the large aircraft above them.

"All of it?"

"Yeah. The Kraang are going to use it to turn all the people of New York into Kraang!"

"What?" cried Raph, stabbing his sai through a robot's eye. "How do we stop them?"

"We need to blow up that ship before it takes off!" Two more Kraang fell crumpled at Leo's feet.

"How?"

"Donnie says the Blue Goo is highly combustible. If we shoot it with a laser gun, it should explode."

"I'm on it!" cried Mikey, suddenly leaping out of the fray and running toward the ship.

At that moment, however, the massive ship suddenly hummed to life. The ramp leading into it was removed, though the hatch remained open, and the four support legs folded up into the underside of the ship. The aircraft hovered for a moment before slowly beginning to rise into the air. At the same time, the enormous garage door began to slide open in order to allow the ship access to the city.

Mikey turned back to his brothers in a panic. "What do we do now?"

Leo did not lose his cool for a moment. "Mikey, do you think you could jump into that open hatch, if Raph and I launch you?"

Mikey glanced up at the opening in the underbelly of the ship, which was gradually rising higher into the air. He turned back to Leo with a grinning thumbs up. "No problemo, bro!"

Leo nodded to Raph and the two of them assumed a crouching position, facing each other. They interlaced their fingers, creating a cradle between them, while Mikey took a few steps backward.

"Now, Mikey!" cried Leo.

The orange-banded ninja took a running leap, landed in his brothers' cupped hands, and just as they threw him into the air, he jumped with all his might. The combined strength of all three brothers worked to send Mikey flying high above their heads. Grasping the edge of the open hatch with his fingers, the boy hauled himself aboard the slowly rising ship.

On the other side of the room, Donnie was smiling as the purple screen in front of him displayed exactly what he was hoping for. Pressing a few more buttons, he suddenly threw his fist into the air, shouting, "Yes! I did it!"

His jubilee was interrupted by the sound of footsteps behind him. He turned to find two Kraang droids coming towards him.

"It is the one who was known as the prisoner of Kraang. The prisoner of Kraang has escaped from Kraang and is attempting to thwart the plans of Kraang. The prisoner of Kraang must be stopped by Kraang."

"Not this time!" cried Donnie vengefully, lifting the gun from his lap and firing. The first droid fell broken at his feet. "Ha!" he shouted with satisfaction, shooting the second robot in like manner. It was impossible to tell one Kraang droid from another, but it gave Donnie pleasure to think that these were the two who had caused him so much pain with their torture stick.

Nunchuks twirling, Mikey had leaped through the open hatch of the Kraang ship and succeeded in taking down the three robots who had been surrounding the opening almost before they had a chance to notice his presence. Now he looked around among the confusing pink and purple blinking lights for the Blue Goo. If all of it was aboard the ship, as Leo had said, then there must be hundreds of jars of it. It would be a piece of cake to snatch one to take home with him before destroying the rest.

Noticing a bluish-green glow coming through an open doorway just ahead, Mikey ducked through it and stopped short. On the other side of the doorway were two immense glass canisters, nearly twenty feet high, one swirling with a green liquid, the other with blue. Mikey just stared at them. He had been expecting portable canisters of Blue Goo, something he could grab and take back to the lair. Looking at the massive tube in front of him however, he knew at once that it would take him ages to find a way to safely steal any of it and bring it back to his brothers, and by then it would be too late to save the city. There was simply no time. But if he shot that giant container, all of the Blue Goo would explode and he would lose his last chance to remain human.

Time seemed to slow as the emotions whirled through Mikey's chest. He thought of his exciting day at school, the friends he had made, and all the things on his list he still hadn't done yet. He felt angry tears prick his eyes at the unfairness of the choice he had to make. He had been so sure that they would manage to take some Blue Goo and defeat the Kraang. Glancing down at his hands holding his nunchaku, his human hands which he so desperately wanted to keep, he nearly lost his resolve. But he knew his decision was already made.

Gritting his teeth, Mikey scowled at two Kraang who had noticed his intrusion and were moving toward him. With one violent swoop, he felled them both and snatched one of the laser guns from their hands.

Then he ran back toward the open hatch, taking down two more bots on the way. Standing right next to the opening, he swallowed the lump in his throat and aimed his gun with a determined air back through the doorway where he could still see the glowing blue fluid just beyond. With an almighty cry of "BOOYAKASHA!" he leaped backward through the hatch, pulling the trigger at the same time.

Mikey was halfway to the floor when the entire building shook with a rumbling explosion, and the Kraang ship veered to one side, spurting flames and black smoke out of one end, taking with it his very last hope of a normal life. Mikey felt strong arms catch him and set him on his feet as Raph's voice said, "Ya did good, bro."

Then they were running together toward the other end of the building, putting as much distance as possible between themselves and the crashing ship, which continued to let off explosions, setting off a chain reaction of fires throughout the high-tech machinery around the room. Mikey was suddenly aware that Leo had joined them and that they were heading toward the place where Donnie was still sitting at a computer.

Mikey wondered for a moment why Donnie didn't leap up and join them, but as he saw Leo rush to him and lift him into his arms, Mikey realized his brother was hurt. He didn't have much time to reflect on that, though, because the explosions around them necessitated that they make a hasty exit. The few remaining Kraang were in a panic and ignored the ninjas as they rushed through the half open garage door.

A massive explosion rocked the ground just as they made it safely out of the building. Without looking back, Leo led them a few blocks away to an alley, half illuminated by the light of a street lamp. They could hear the sirens of fire trucks not far away, but Leo knew they wouldn't be spotted here.

With Raph's help, Leo gently lowered Donnie to the ground, leaning his back against a wall.

"Now," said Leo, "let's take a look at that leg." Carefully he loosened the laces of Donnie's shoe as much as he could, and with great care he began to slip it off his brother's foot while his other brothers watched, their faces etched with concern.

Despite Leo's careful gentleness, Donnie still let out a whimper as the shoe was removed, followed by the sock. Raph scooted closer to him and put an arm around his shoulders, giving him a hand to squeeze. Mikey glanced curiously at Raph's display of tenderness, and wondered if he felt bad for assuming the worst of Donnie when he hadn't shown up for the mission earlier.

Leo cradled the injured ankle in his hand as he pulled a bandage out of his pocket. Donnie glanced down at his ankle and saw it was black and blue and swollen to nearly twice its normal size. He squeezed his eyes shut and took a deep breath as occasional residual tremors still shuddered their way through his body.

"OK, Donnie," Leo said. "I'm going to wrap it tightly so that it won't move around too much on our way home. Once we're there we can set the bone properly."

Nodding his consent, Donnie set his jaw as Leo began the process.

"Donnie," Leo asked hesitantly, "Is this what the Kraang were doing when we heard you – you know – over the phone?"

Donnie opened his eyes and shook his head. "No," he said softly. "No, it was the - the metal rod - that - that Mikey told us about – " He spoke haltingly. "They - they pressed it to my neck and – " His breath caught in his throat and he found he could not bring himself to say any more as the memories of his nightmare experience flooded his mind.

Mikey patted Donnie's leg sympathetically. "Say no more, bro. I know what that thing does."

Raph gave his brother's shoulders a rough but reassuring squeeze, which Donnie understood to mean he didn't have to talk about the ordeal right now if he didn't want to. Words of comfort had never been Raph's strong suit, but the sentiment was there.

Donnie nodded in response, then suddenly took a quick intake of breath as a pain shot up his leg, despite Leo's best efforts at tenderness.

"Oh, sorry, Donnie!" apologized Leo as his brother turned and hid his face in Raph's shoulder with a moan. "I'm nearly done." He tied off the bandage, and then quickly wrapped one around the wound in Donnie's upper arm, as well, although the cut had long since ceased bleeding on its own.

After Leo was satisfied there were no more injuries, they were at last ready to continue. Raph and Mikey helped Donnie onto Leo's back where he wrapped his arms around his older brother's neck and prepared for the journey home. His nervous system seemed to be recovering at last, for he was no longer trembling so much, and he found he was able to maintain a firm hold.

The boys ran as fast as they could for several miles, Leo doing his best to run smoothly so as not to jostle his brother's injured leg too much. Despite his best efforts, however, Donnie kept whimpering and hiding his face in the back of Leo's neck. On top of this, the blue-banded ninja was experiencing those strange tingling sensations more frequently. The third time it happened, it was in his right foot, and he stumbled, causing Donnie to cry out and cling to him more tightly.

"Sorry, Donnie," Leo apologized, regaining his balance. "My leg went numb again."

He called a halt and they all ducked into a nearby dark alley, surrounded by abandoned buildings and occupied by nothing but a dumpster and some graffiti. He gently lowered Donnie to the ground, and his purple-banded brother leaned against the rough brick wall of the alley, eyes closed and teeth clenched.

Raph stood with his hands on his hips, looking at their leader. "Why are we stopping?" he asked. "We're still miles from home!"

"We need a break, Raph," said Leo, resting his hands on his knees to try to catch his breath, then, noticing the incredulous look on his brother's face, he clarified, "I need a break. And Donnie's in pain. We can't push him too hard. Plus, I keep getting – " He was about to mention the increasing periods of numbness when he suddenly noticed the expression on Mikey's face. His youngest brother had hardly spoken a word since they left the Kraang facility, and now Leo thought he looked like he was going to cry. "Mikey, what's wrong?"

"Nothin'," mumbled Mikey, shoving his hands in his pockets and kicking a discarded soda can in a way that meant the opposite of nothing.

"Mikey. . ." began Leo, stepping toward his brother.

The usually cheerful boy looked up, his blue eyes swimming with tears. "I was supposed to meet Justin and Ryan at the skate park tomorrow afternoon!" he suddenly blurted out. "We were going to hang out and go skateboarding, and they were going to be my friends, and now I won't get to do any of that, and they'll think I didn't want to be their friend!" The tears spilled over and stained his mask before trickling down his freckled cheeks.

"Oh, Mikey," Leo reached for him, but Raph was quicker.

Putting an arm around his baby brother's shoulders, he said in a sincere tone, "You were really brave back there, Mikey."

Mikey sniffed and looked up at his brother.

"Honestly," Raph continued, "blowing up that canister of Blue Goo when you knew it was the only one. You saved the city, Mikey. You made the right choice."

Mikey nodded and seemed to be somewhat encouraged by his brother's affirmation.

Suddenly Donnie's voice came from the shadows near the ground. "Guys, do you feel that, too?" He was holding his hands in front of him. "Both of my arms are all tingly and numb. Oh, and my legs, too!"

"Mine, too!" cried Mikey. "Oh no! It's starting, isn't it? We're changing back!"

"I think you're right, Mikey," Leo said nervously. His legs started to give way and he knelt down beside Donnie, grabbing his brother's hand as the two of them prepared as best they could for the unavoidable mutation.

"No! I don't want to! I don't want to! Raph, help!" Mikey was panicking and clutched at Raph, hiding his face in his big brother's chest.

Raph wanted to comfort Mikey, to tell him it would be OK, but he knew it wasn't OK, and he didn't know what else to say to his frightened little brother. So he let his strong arms speak for themselves as he wrapped them tightly around his brother and gently pulled him down to a sitting position. He was powerless to prevent the mutation, but he could at least ensure his baby brother did not have to go through it alone this time. He held Mikey close, determined not to let him go, no matter what happened.

Mikey closed his eyes, trembling as the cold numbness spread over his body. Any second now, he knew. . . Searing pain shot down Mikey's spine and he cried out, burying his face deeper into Raph's chest, trying to block out the pain and muffle the cries and groans of agony coming from his brothers a few feet away. He shook and writhed uncontrollably, unable to contain the screams, clinging to Raph as to a bulwark through the storm.

Raphael steeled himself against the pain, willing himself to be strong for the sake of his little brother. Despite his own suffering, he never slackened his protective grip around Michelangelo.

At long last the torment ended and relief swept through Mikey's trembling body. He nuzzled his face against the familiar smoothness of Raph's plastron as strong hands rubbed the back of his shell soothingly.

"It's alright, Little Brother," came a gruff but comforting voice in his ear. "It's over now. It's all over."

Mikey opened his eyes and looked down at his hands. They were his own again. He stared at the familiar green fingers for a moment before pressing himself deeper into Raph's embrace and bursting into tears.

Leo stood up and stretched, flexing his muscles. Being a human had certainly been an interesting adventure, but if he was honest with himself, he was glad to be back in his own body again. He glanced down at Donatello and saw his olive green face was pale. Both his fists were clenched and he was breathing heavily. Clearly the mutation had been hardest on Donnie, who was still dealing with the pain of his broken ankle.

Donnie looked down at himself, taking in the familiar sight of his lanky green arms and legs, his three fingered hands, his smooth shell. He was a mutant again. A quivering sigh escaped his throat. Deep down, he felt that he had known all along that it couldn't last, and he had to come to terms with that.

"Come on, Donnie, let's get you home," Leo said, gently lifting his injured brother onto his back and gesturing for the other two to follow.

Swiftly and silently the ninjas moved through the shadows. They were outcasts once more, and could not risk being seen. Yet they knew, hidden underground was their own safe haven, filled with welcoming warmth and love. And their father was waiting for them.

FINIS

A/N: I hope you like the way everything turned out in the end! Thanks to all of you who stuck with me through this story. Drop me a review because I'd love to know what you think!