Hey, guys; thanks for clicking :) Okay, so this fanfic starts when Shredder as the Utrom has been "killed" at that place that was acting as a base for the surviving Utrom population when it blew up. (If anyone can remember the name/acronym of that place, it would be really useful to know.) The plot pretty much follows the same as the episodes, with a few added extras. Hope you enjoy chapter 1.

Fly on,

NitnatRide

Chapter 1: Disturbance

Donatello's POV

My brothers may be too distracted with their training and all the action that's been happening around us lately, but I haven't forgotten the promise we made to our friends in the underground; we said we would return to them with a cure so that they can leave the underground cavern without turning back into monsters. And I'm never going to give up trying to do just that.

But how the shell am I supposed to do it?

I groan again as I spend another wasted minute at my desk gazing at the crystals with no clue of how to break them down. I know I have to, but nothing seems to be working.

Before I can fully go insane, however, a bleeping cuts through my frustrated thoughts, and I sit up, curious. Turning back to the source – my computer – I realise one of the many sensors I have laid about the city and other places has been triggered. Interestingly and appropriately enough, it's one from the underground. The bad news is the sensor that's been triggered is outside of the cavern, away from the Crystal Moon's light. I quickly list through the different reasons for this happening; my friend's wouldn't venture from the light, as they know what would happen if they did. That is, unless they were reverted back to savage monsters in the first place.

Before I can allow myself to panic further, I click through the data received from the sensor…and frown.

"That's strange," I mutter to myself, turning completely to my computer and opening a more detailed set of the data.

"What's up, Don?" Raph stops kicking the stuffing out of the poor punching bag, taking a breather and joining me by my equipment.

"I set up some sensors in the underground before we left, and one of them was just set off," I explain. "It was out of the range of the Crystal Moon though, so I got worried, thinking maybe one or all of our friends have changed back into monsters. But when I looked at the data detected by the sensor, it's like nothing I've ever seen. As in 'not even monsters', nothing I've ever seen.

"According to the sensor, who- or whatever set this off is a mixture of both technology and biology. I would originally have thought they had a microchip or some other kind of tech equipment with them, but both the biological and the technological systems and signals seem to be working simultaneously…almost working together."

"I got about half of what you were saying," Raph admits, "but I'm getting the vibes that whatever this is ain't normal."

"Not at all," I agree. "You know there's basically a modern day war going on between biology and technology? Human workers are being replaced with machines, and all that? Imagine not having that war. Imagine both systems being able to hold hands in the same space and time, without any conflict."

"Whoa."

"Definitely whoa."

"What videogame you two playing?" Mikey jumps over from the TV area, and Leo joins him to see what the gathering is about.

I throw him a look over my shoulder. "Not everything about computers is about videogames, Mikey."

I relay the new information to Mikey and Leo, and – after explaining a few more times to Mikey, in simpler words – we all agree that whatever is down there isn't one of our friends.

"We should go check it out," Leo says, pushing back from the desk, and I stand up to join him, beginning to gather some gear to help us when we're down there.

"Back to the scary underground place?" Mikey clarifies. "Nuh uh. No way. I'll stay here, thanks." He turns to walk back to the TV.

"Okay," I smirk, slowly making my way to the sewer door. "You can stay here and tell Master Splinter where we are when he comes out."

Leo smiles sideways at me, and we share a look.

Five, four, three, two, one…

"On second thought, wait up…"

ЖЖЖ

As we descend into the underground again, I make a mental note to use some of the Utrom technology to build something that'll make navigating through this place a whole lot easier.

Halfway to the first sensor that was triggered, I pick up another disturbance on a different one, further down the same tunnel route as the first. The curious readings are the same, confirming that it's our mystery guest. We follow the trail set for us, on alert for any kind of attack, even though our friends were human last time we saw them.

We find ourselves in one of the genome labs, with the shield generator in the middle, even if the crystal fuel is absent. The computer screens still glow faintly, and the crystals I brought down add to the eerie glow in the room. Glancing around in the semi-darkness, I can't shake the feeling that we aren't the only presence here. And I've always been told to trust those feelings.

I trust them just a second too late; all the computer screens suddenly black-out, the darkness so surprising that none of us are prepared. I hear Raph cry out, and instantly drop my bag, drawing my bō staff ready against any sign of another attack. But another second later, the screens flash back on again, illuminating the room. I spot Raph on the floor, still conscious.

"You okay?" I check as he gets to his feet.

"My sai!" he cries, ignoring my question. "One of my sais has gone!"

Flicking my gaze to his belt, I realise he's right; only one sai remains stuck in the belt.

"That damn coward stole my sai!" Raph shouts, indignant and looking ready to commit murder. I guess he's fine then.

"Did you see them?" Leo asks, leader hat on while still scanning around us.

"Nah, they came from behind," Raph growls.

"Alright," Leo says, sheathing his own katana. "Let's keep moving; they can't have gotten far, so we should catch up with them."

"Yeah, this tunnel only runs this way, and I think I heard whoever or whatever it was going that way." I point towards the way we were heading before the attack.

"Let's go then," Raph insists, taking off at a run.

"Be careful, Raph!" Leo calls, running after him. "We need to be alert and cautious."

"You wouldn't be saying that if it was your katana that was taken," my angry brother retorts.

"Fair enough," Leo mutters.

Looking over my shoulder at my remaining brother, I gesture to the others. "Come on, Mikey."

"Right behind ya," he agrees, following me and chasing after the other two.

After a few minutes, a bleeping alerts me to the fact that another sensor has been triggered, this time in the next genome lab. Interestingly, I remember planting other sensors on the exit of that room, and yet my computer says that that sensor hasn't been disturbed. That means the presence is still in that lab.

Recounting my theory to the others, we approach the next lab more slowly, keeping to the shadows and staying completely silent in order to catch our opponent unawares. Strangely, the noise coming from the lab suggests that our opponent isn't expecting us to follow them, which seems a strange assumption if they are trained in Ninjitsu. We sneak round the corner, hiding behind a set of pipes, before glancing around the edge. Upon the sight, I freeze in confusion, and can sense the same bemusement from my brothers.

It's a girl, about the same age as us; no more than eighteen. She's facing into the far right corner of the lab from where we're standing, slightly turned towards us so we can see her features, but not enough that she would spot us in her field of vision. Large waves of hair, the colour of April's – if a little more red, rather than purple – fall to halfway down her shoulders. Raph's sai is in her hands, pushed into the lock of the glass cabinet she's facing, obviously trying to get it open, and her eyes – a really intense green, again like April's – are narrowed in concentration. Her white T-shirt with a flower design on the front is obviously dirty and old, as are her jeans, both fraying at their edges and with tears dotted about them.

As I narrow my own eyes, I see the cabinet she's trying to break into still has what looks like medication inside. She growls in frustration, throwing the sai to the ground, displeased with the lack of result, and now that she's not doing anything, I can see for the first time that she's shaking. Not with rage or any other emotion; more like uncontrollable convulsions. She smacks her trembling fists against the glass hard, and yet it doesn't even crack. It must be some kind of Utrom glass, resistant to almost any kind of force.

Suddenly the convulsions worsen, and her whole body begins to shake violently. She sinks to the floor by the cabinet, folding her arms around her knees, now drawn up to her chest, and begins to sob quietly.

"Don't let me die down here," she whispers, her words broken because of her shaking form. "Please, don't let me die down here. Not here."

"Seizures," I say almost silently, speculating to myself and the others. "Withdrawal symptoms to something."

We look at each other at the same time, all coming to the same conclusion; whatever she was trying to get out of the cabinet, she needs to be able to survive the next few hours, if not minutes. Raph grimaces in annoyance, and I know he's making one of those decisions that he knows is right but doesn't like.

"You're doing it wrong," he calls out, loud enough for the girl to hear.

She gasps, turning towards Raph's voice and trying to jump up. She fails, her body trembling too violently for her to hold herself up, and she collapses against the cabinet again, still staring in our direction. We all walk slowly from behind the pipes, trying to look as unthreatening as possible but ready to draw our weapons if she decides to attack. I don't see what harm she could do in the state she's in though.

Raph walks further towards her while Mikey, Leo and I stay back, so as not to make her feel threatened. Raph takes his sai from his belt, holding it loosely, and continues to walk towards the girl. Amazingly, she stands her ground, but fear is quite evident in her eyes and expression. My brother comes to a stop by the cabinet, and inserts the sai into the lock.

"You gotta be gentler with it," he explains, twisting his weapon in the lock slightly. It clicks open.

"Whaddaya need?" he asks, pulling the cabinet door open and looking down at the girl, now on the floor again.

She stares at him, her eyes wide, but more in disbelief that he's helping her, rather than fear because of his exterior.

"Tryptophan," she says after a few seconds of silence, pushing her hair out of her eyes.

Raph searches in the cabinet, eventually pulling out a capsule bottle, checking the label one more time before handing it to her.

"Sorry I don't have anything to help you swallow them," he says.

"Thanks," she gives a small smile as she unscrews the cap. "Don't worry; I've taken them dry before."

Shaking two small white pills into her hand, she tips them into her mouth, tipping back her head as she swallows. After a few seconds of awkward silence, with neither me nor my brothers knowing what to say or do next, the girl acts for us; her body still shaking slightly – though not as violently – she slowly and obviously reaches over to Raph's sai on the floor. Grabbing the blade gently, she picks it up and holds it out to Raph, handle first. He seems surprised at first before he stretches out and takes hold of it, carefully pulling it out of the girl's grip so as not to cut her.

"I'm sorry I took it from you," she says quietly, "and for knocking you over. I just needed something to pick the lock."

Raph nods silently to her, and I read between the lines of that gesture; he's saying 'I kind of understand your position, and probably would have done the same, but you still stole my sai, so I'll give you a bit of time to redeem yourself'.

As her body begins to fully calm down, Leo can't hold the interrogation in any longer.

"How did you get down here?" he asks, as gently as he can. "How did you know the medication you needed was down here? And why do you need it in the first place?"

She just smiles at him, her expression saying that she understands his curiosity and frustration. "It'll take a while for me to answer all of those questions," she admits. "First, introductions; you guys go first, because my introduction will just raise more questions as well as bringing us nicely onto your first ones."

My brothers and I look at each other, confused, before responding to her request, introducing ourselves respectively while Raph sheaths his sais. The girl smiles at us all, curiously undisturbed by four five-foot, talking turtles.

"I don't know what name my birth parents gave me," she confesses, and I blink in surprise. "Or if they even gave me one in the first place. But I've always liked the name Kelly, so that's what I go by."

We glance at each other again, confused by the fact that she doesn't know what her name is, but she doesn't continue. Instead she looks around, uneasily.

"I don't mean to be rude," she says, turning back to us, "but can we continue this discussion on the move? I don't want to spend any more time in this place than necessary."

Sharing looks between ourselves again, Leo, Raph, Mikey and I nod to each other, and Raph holds a hand out to help the girl up. As we start walking back the way we came, my mind is going a hundred miles an hour trying to find answers.

She could have been orphaned at birth, but she still would have had a birth certificate, with her name on. And how does she know about this place? The fact that she's uneasy in here suggests that she knows what went on down here. Wait…

Suddenly having a brainwave, I spin back to Kelly, pointing my finger at her. "You're an experiment! You're one of the Foot's experiments!" I stutter at the end, realising that I was both extremely rude and probably scaring her with my intensity. Lowering my finger, I smile apologetically. Surprisingly, Kelly grins at me.

"You're a smart one," she compliments me, and I've never been more pleased that my biology leaves me with an inability to blush.

"So, you're one of the experiments," Leo says as we continue walking. "That explains why you're not shocked at the sight of us."

"I've seen way weirder things," Kelly agrees. "And way more horrible."

"I'll take that as a compliment," Raph mutters.

"We know other people who were experiments," I explain. "They're human now, but they're trapped down here now, because they can't stray too far from the crystals found down here, or they turn back into monsters."

"I may know a few of them," Kelly says, looking happy that some of her friends might be alright now, but sad that they were caught up in it in the first place. "My story isn't like theirs though; for one, they were fully grown humans when they were taken for experimentation. My genetics were actually messed up before I was even born, using a method called amniocentesis."

"Messing with a foetus while it's still in its mother's womb," I automatically translate for the others, Mikey specifically.

"Exactly," Kelly nods. "But I'm like nothing the Foot has ever done before, and they don't know they succeeded."

"You're right about the 'like nothing ever done before' bit," I say, turning back to her excitedly again, my curiosity getting the better of me. "I checked your genetic make-up on my sensors that you set off down here, and it's unbelievable; both biological and technological, but working at the same time."

She stares at me with an odd look on her face for a few seconds, before smiling slyly. "You're the techno-geek of the family, huh?"

I smile sheepishly. "Uh, kind of, yeah."

Raph punches my shoulder lightly. "Stop being modest." He turns to Kelly, a proud smile on his face. "You want any kind of gadget, Donny's your man. Well, turtle."

Kelly laughs. "Well, you're gonna love me, from a scientist and techno-geek point of view. You heard of merging human DNA with that of other creatures, like cats and other stuff?" We all nod.

"I read about people doing that stuff in comics," Mikey says proudly. Kelly chuckles, already getting a good judge on Mikey's character.

"Well, the Shredder and his lackeys did the same stuff to me, only they didn't use animal DNA. My DNA is a mix of human, and the DNA equivalent in a computer."

I can't help it; I freeze and stare at her, my mouth hanging open like an idiot. She glances back over her shoulder, grinning at me again before continuing to walk forwards. I hurry to catch up.

"I can connect to any kind of technology around me," she continues, "and talk to it, asking it to do stuff for me. I can tap on to any electro-magnetic wave around me, hijacking it. I can actually enter into any technological equipment and travel down them; usually it's cell phones, because they have to connect with each other, so it's easy for me to skip from one place to another. Anything I think of doing, like cooking a specific dish or doing a cool dance move, I can automatically do them."

"How does that last one work?" I ask, unable to quell the scientist in me.

She smiles at me. "I have full-signal, unlimited and constant access to the internet in my body. There are so many step-by-step guides on there, it's incredible. But normal humans can only read them, and their success in whatever their doing depends on the competence of their body. Because the internet and my body are basically one and the same, as soon as I think about it, my body automatically knows how to do it." She directs her attention to Raph. "That's how I was able to knock you on the floor and steal your sai basically before you'd blinked; I thought up some kind of Ninjitsu moves that would allow me to do that, then told the computer screens in the room to die for a few seconds before I conducted the moves. Of course, the presence of the four of you helped with thinking up Ninjitsu moves."

"That's so cool," I whisper, imagining all the things this girl could be capable of.

"What do you mean our presence helped?" Raph frowns.

"Every single brain capable of memory is much like a database," she explains. "It stores information, and the user can retrieve it when they need it. Since I can access any kind of database – I once hacked into the CIA, so security systems are nothing to worry about – I can access the information in people's memories, and learn about the different Ninjitsu moves possible, for example. As soon as I saw a move that looked like it would help me retrieve the sai, my body automatically searched for the move and the instructions on how it's done, and I could then do it. It sounds more complicated than it actually is; now that it's instinct for me to do something like this, that whole process takes me on average two or three seconds. Five seconds, tops."

"That fast?" I breathe, my eyes nearly popping out of my head and dislodging my mask.

She, unbelievably, gets all shy, giving a small smile and shrugging modestly.

"So what's with the pills?" Leo questions, gesturing to the bottle still in Kelly's left hand.

This time, Kelly's smile is unbearably sad. "Every abnormal freak of nature that should never have been created has design flaws." She goes on before I can argue with her self-perception. "Mine is the fact that my human body needs all the stuff that normal humans need, like a hormone called serotonin. It's basically a hormone that keeps you happy and helps growth. My body doesn't produce any serotonin, so I need external help, like from these tablets or a glass of milk, or I start to crash, like you saw back in the lab. It starts with seizures like that, then I've worked out that I basically have thirty six hours – forty eight at most – to get supplements like these. If I don't get them in that time, I'll die of heart-failure."

The confession of the real fragility of her life shocks my brothers and me into a long silence before Leo frowns, obviously upset.

"How can you say such a thing so matter-of-factly?" he demands.

Kelly shrugs, and because I agree with Leo, her nonchalance annoys me.

"I've lived with it all of my seventeen-or-eighteen years of life," she says. "It's the same as someone born with asthma or anaphylaxis; they've suffered from a potentially life-threatening condition, and they've just got on with life because they've become accustomed to that threat."

"You shouldn't have to live with that though," I scowl, thinking about the Foot's cruel experiments.

"I shouldn't have to live, period," Kelly laughs once, hollow of any kind of humour. "I'm not natural, Donny, and it's not right for me to be alive."

I stare at her in shock, barely believing my ears, barely believing that someone could ever even think that about themselves.

"We're not natural," Mikey points out, being unusually observant and serious. "Does that make us wrong? Mistakes?"

Kelly says nothing, looking toward the floor in shame, her red hair brushing against her face, and the light makes it look horribly like a meandering river of blood running down her face. "That's not what I meant," she whispers.

Leo sighs, and I sense he's going back into leader-mode. "Whether any of us are wrong or not, we're all here, so we need to work in the present to make the future. Where have you been staying since the lab was shut down and you obviously escaped?"

Kelly shrugs again. "Up top, on the streets anywhere around New York City. Wherever there was a space where I was less likely to be harassed by Purple Dragon punk wannabe-gangsters, I'd stay for the night."

Again, I frown, not liking the fact that she'd had to survive on the streets alone for so long.

"Well, we've got a place that'll be a lot more comfortable than the streets. It's in the sewers, but it's clean. And it's home."

"I found an extra room too, so Mikey won't have to share with Raph again," I point out, before my brother can complain.

Kelly stares off into the distance, her eyes unfocussed, as she considers our offer. Eventually she turns back to Leo, a warm smile on her face even as her eyes startlingly fill with tears.

"A home sounds great right now," she agrees.

Kelly's POV

I can't believe these guys are being so nice to me. Especially Raph; I did knock him over and steal his sai, and from a look in Donny's memories, his weapons are everything to him.

We walk further along the tunnels in companiable silence, and my excitement puts a spring in my step, so much so that I surprise them when I follow their flips perfectly as we surface up to the sewers. I shrug off their impressed looks, reminding them of my hyper-kinesis – the ability to perform everything perfectly – and the Ninjitsu training I automatically learnt from their minds.

Considering I've slept anywhere I could on the New York streets, I have no qualms about wading through sewer water as we climb into the underground maze.

"Think you can keep up if we run?" Raph asks, actually genuinely concerned.

"Bite me," I grin, feigning indignation. "You're forgetting that my new ninja moves make me faster, and that I've been running my entire life outside of the lab. The only thing that's stopping me from challenging – and kicking – your reptilian rear at a footrace back to yours is the fact that it's rude to burst first one into a house to which you've been invited, especially if it's your first time there."

You would think a hamster had just snarled at the guys the way they're looking at me. I begin to get extremely self-conscious, worried that I'd offended Raph, before they all burst out laughing, and I join them in relief.

Eventually, when they've all calmed down, Raph slings an arm around my shoulders – easily, due to my measly 5'5". At least I'm a bit taller than these guys – and grins.

"Alright then," he says. "We'll lead, but you have to keep up. Let's see these mad skills you got then, kid."

I mock bow to him, gesturing to the right. "Lead the way, oh great one."

He takes off running with his brothers in tow, and I push myself forward, all of us laughing at the thrill of the mock chase as I catch up easily. The guys battle for the lead constantly, the fight mainly between Raph and Leo, while I contented myself to follow. For now; as soon as we're familiar enough with each other, I'm so going to prove that turtles are still really slow, whether genetically mutated or not.

When we get to a weird-looking teal-coloured door, we stop, obviously signifying the end of the race. All of us are barely breathing hard.

"Not bad," Mikey grins, nodding to me.

I flip my eyebrows in response, grabbing at an imaginary skirt and raising it slightly while bobbing once on my knees in a mock version of a curtsy.

Leo and the others walk forward, and I follow behind as the weird doors open automatically.

"Welcome to our humble abode," Leo grins.

Their home may be in the sewers, but it's not "humble" by any means. The wide, open circular room that we've stepped into has a main "arena" space in the middle, while the raised walkway runs all around the room, with ramps descending from four opposite points into the arena section. Off to my left, on the walkway, lies a "lounge" section with so many TV screens I can't count, and more computers and other tech to the right of couch. Those weird designs I saw on the door are dotted all around the lair. The whole place is made of stone.

But, since the guys have seen all this amazing stuff before, I'm thinking they're not bothered by the architecture or the equipment. I should think they're more concerned about the robed giant rat standing in the centre of the arena, a scowl creasing his furry forehead and his arms folded firmly as he glares at my new friends. From Donny's memory, I recognise him as Splinter, the master and father of the four brothers around me.

"You didn't…perchance…sneak out, did you?" I smirk and raise my eyebrows at all of them.

"No," Mikey squeaks, desperate for his master not to donate his hide to the shoe-making industry.

I glance back at Splinter. He did not look happy.

"Busted," I warn the turtles.

Let me know what you think :)