Please check the Author's note at the end!

Beta'ed by Lohis, thank you! ^^

Disclaimer: I don't own Naruto or Transformers Prime

Will of Fire and Hearts of Steel

Chapter One

Kakashi woke up with a killer headache.

He felt like he'd been on a month-long mission around the Five Great Countries, then been ran over by a swarm of hyperactive pre-genins and finally been beaten up by an angry, no, furious Tsunade. He was completely drained and almost sure something was trying to hammer its way out from inside his skull. Only years of ninja training kept him from groaning aloud and curling up into a pathetic ball of existence.

Instead of doing just that he decided to find out where he currently was. He tried to gather up his chakra so he could examine his surroundings and investigate possible presences around him before giving away his awakened state. He immediately almost winced. His chakra reserves were practically non-existent. He mentally frowned, wondering if he'd really been on a month-long nightmare mission. He hadn't felt this weary for ages…

That brought the Copy Nin to another problem. What exactly had he been doing before passing out for a moment (he thought it had been a moment, of course he couldn't be sure)? There had been a mission, he recalled. With his team, now consisting of Naruto, Sakura and that little creepy fellow Sai. Yes, they had been on a mission together on the borders of the Fire Country. Chasing some rogue nins, who should not have been above the rank of a mediocre chuunin. But of course the preliminary information had once again failed them and one of the rogues had been almost jounin-level. Fortunately there had been just three of them, and his team had performed almost flawlessly (for once). They had managed to knock out one of the enemies without any serious injuries. Kakashi had just been taking out the second one when the third had managed to surprise him with a jutsu he had never seen before (a true shame he hadn't seen the rogue nin form the seals, it would have been very interesting to learn that technique with the Sharingan).

Kakashi remembered seeing a ball of blinding light speeding towards him. He had easily leaped away from its course, but the weird light had turned and followed him with alarming velocity. So he had activated the Mangekyou Sharingan, hoping to catch the jutsu with his Kamui before it would hit him.

He remembered seeing Sai and Sakura circle behind the last rogue nin, about to knock her down. He recalled hearing Naruto shout something. The ball of white light had been close, so close but his Kamui had been ready too…

What had followed next had felt like an explosion without the heat. He remembered Naruto's surprised yell, and then everything was white and then black.

And that was all.

Kakashi tried to open his right eye, carefully keeping the Sharingan closed. He didn't know if Obito's gift would be inactive from all the exhaustion, or if it would just drain him dead on the second he opened it. For a moment his vision was blurry and he slowly blinked, trying to clear his gaze.

He heard a soft groan from somewhere to his left. Naruto. At least the boy was alive. He didn't know if the explosion had been caused purely by the unfamiliar jutsu or was it the combination of that and his Kamui. Anyway, Naruto seemed to have got caught up in it as well.

"Naruto?" He called his blond student's name.

"Owwwww… My head hurts…" Naruto complained, but sounded otherwise alright. Good. He blinked some more and slowly pushed himself off of the ground, finally standing again. He needed to make sure his other protégées would be okay too.

He stared at his surroundings.

It looked like a desert. The ground was reddish and dusty, and great rock formations rose towards the darkening sky. A soft breeze ruffled his already messy silver hair. It was quiet and deserted. There was nothing in sight as far as he could see.

Where the hell were they?

"Woah… WOAH! Kakashi-sensei, where the hell are we?"

The elite jounin didn't reply. Indeed, where? They had just been fighting in a forest, damn it! On the borders of Konoha! First Kakashi had thought they might be in Suna, but he'd been there plenty of times and didn't think this was it. He'd never seen a place quite like this, and he had traveled all around the Great Countries.

"Well, I don't think we're in Konoha anymore, Naruto," Kakashi said, tugging down his hitai-ate so it was tilted over his left eye.

Naruto, who had also scrambled up from the ground, turned wildly around and stared at the huge rock formations.

"Almost… almost like Suna, but it kinda feels different…." The blond muttered, and Kakashi thought once again that the kid could be smart when he wanted to.

"Yeah, I thought that too…"

Naruto turned to meet his gaze and frowned.

"Do you… Do you think Sakura and Sai are okay?"

Kakashi didn't honestly know, but he had a feeling.

"I'm pretty sure they're fine. We had almost already won, and they are quite competent fighters after all."

Naruto nodded, looking relieved. Then he continued staring at their new surroundings.

"What do you think happened, Sensei?" The boy asked.

Kakashi scratched the back of his head. If this was a genjutsu, it sure was a weird one. And Naruto was here too, looking very real. Could it have been some weird transport jutsu? He had heard something of techniques like that. And he didn't know all the secrets of the Mangekyou either. There were always stories going around about jutsus going wrong and colliding and so on. He just had never experienced a thing like that before.

"I'm not sure, but I have an idea. But first, how are you feeling?"

Naruto grinned at him. "I'm okay!" He declared. Then he smiled sheepishly. "Though I feel quite jaded. I don't think I could even do a single shadow clone." So, even Naruto's seemingly endless chakra reserves were almost empty. Then it hadn't been just him overusing his Sharingan again. Must have been a side-effect of the explosion.

"Well, we'll probably have to rest a bit. I don't know what that explosion of light was, but it surely drained us both." He rubbed his masked cheek and cautiously eyed the weird world they had been thrown into.

"And let's be careful. We don't know a thing about this place, and now would be a very bad time to bump into any hostile individuals."

There was a loud clatter, followed by a metallic thump and a screeching noise. The ball of scrap flew through the air and landed neatly in to the "goal". Bulkhead's shout of victory was quickly followed with a groan from Smokescreen and cheers from Miko and Rafael. Bumblebee beeped and chirped excitedly, clapping loudly.

"YEAH! Five-to-two for me!"

"Aw come on! That was practically cheating!"

"No it wasn't! Bulk doesn't cheat! You're just annoyed 'cause he totally owned you!"

Smokescreen scoffed at the comment, but picked up the ball again and the game continued.

The players and their audience were all oblivious of the white-and-red mech standing beside the screens, glaring at the others every now and then and shaking his head in indignation.

Ratchet sighed. That stupid basketball game sure was a pain. Was it really impossible to have even a moment's peace? This was supposed to be a secret base after all! He needed even a little bit of silence to concentrate on his work. Well, at least Wheeljack wasn't currently here. He wasn't sure he could have dealt with the ruckus Bulkhead's annoying friend would surely have caused. After all, the Wrecker was a totally incompetent ruffian. Well, he was a fellow Autobot too, but Ratchet was still relieved the Wrecker didn't spend too much time at the base.

Muttering angrily to himself, the medic tried to block out the sounds of the game and kept his optics locked on the green screens. Why was he trapped in here with these hyperactive beings anyway? Didn't they have anything better to do? And it was Saturday, so Miko too had made her share for the current high volume levels.

"Woah, a great one Bulk!" The girl yelled when the ball once again hit its goal. Ratchet suppressed a groan of frustration.

"Has there been anything to report, Ratchet?"

Hearing Optimus Prime's grave voice, Ratchet glanced over his shoulder at their leader, who had just entered the room. Finally there was someone who wasn't caught up in that loud game or making totally unnecessary and horrible noise.

"No, nothing. All's quiet."

Clatter. Thump. Cheering.

"In a manner of speaking…" Ratchet muttered.

Suddenly there was loud beep and the medic's gaze was within seconds focused on the screens again. The game behind him stopped instantly as the kids and the rest of the 'Bots curiously turned their attention to the medic.

"What is it, Ratchet?" Bulkhead asked, walking a little closer. Ratched didn't immediately reply and instead checked the data in front of him a few times. Well, this was fascinating indeed.

"There's some activity not far from here, in the desert."

Prime came to a halt beside him. Ratchet's optics narrowed slightly.

"The energy is similar to one of a ground bridge… But it definitely isn't a ground bridge.…"

"Wow Ratch, that's so helpful. Is it a ground bridge or not? Make up your mind already!"

The medic ignored Smokescreen's comment. He glanced at Optimus. "I've never seen anything like this. What do you think it is? Decepticons?"

"Well, if it's not quite a ground bridge, I doubt it's 'Cons then," Bulkhead pondered aloud.

"But could it be a trap?" Rafael asked. The boy pushed his glasses further up on his nose, staring first at the screens and then at Ratchet.

"We can't be sure," the medic replied. "It's nothing like the earlier encounters with Decepticons. Of course Megatron could have invented something completely new." He stared at the data on the screen, sincerely hoping that wasn't the case.

"But what if it isn't them," Bulkhead insisted. "What's going on then?"

There was a short silence, after a moment broken by the Prime.

"If this isn't the doing of the Decepticons and we have learned this information about the ground bridge-like energy, then we have a reason to believe so has Megatron," Optimus stated. "This must be promptly investigated. Ratchet, prepare the ground bridge. Bumblebee," their leader turned around and addressed the yellow Autobot. "Go and investigate. Request reinforcements immediately if the situation so requires."

Bumblebee chirped affirmatively. Ratchet made the preparations and hit the switch. The green glowing ground bridge flared to life before them. Ratchet watched as the yellow Urbana 500 raced through the portal tires screeching and wondered what the young scout might find. Was it a trap by Megatron? Or perhaps by Starscream? Or something completely different?

Rafael walked beside the medic. The boy stared after Bumblebee, looking just a little worried. Raf glanced at the white 'Bot quickly and asked.

"What do you think it is? Will 'Bee be alright?"

Ratchet shut down the ground bridge and held his gaze at the dying green glow. "I honestly don't know. But don't worry, Optimus will send help for Bumblebee if he needs us."

Rafael nodded and joined Miko, who was pestering Bulkhead about the weird occurrence with her usual loud voice.

Almost right after the bridge had ceased existing there was a sound of motorcycle's engines roaring, and Arcee and Jack sped from the tunnel, stopping right in front of the group.

Jack climbed off and removed his helmet. Arcee transformed beside him, straightening and crossing her arms. The dark haired boy's gaze stopped at them all one at a time and with a little frown he asked:

"Um, did we miss something?"

Kakashi had barely finished his sentence when there was a weird sound and a strange green glowing behind them. Kakashi spinned around, two kunais immediately in his hands. Naruto had also turned to face the weird light springing to life before them, lighting up the rapidly darkening evening.

"Sensei…" Naruto trailed off, green glow reflecting from his azure eyes.

Kakashi stepped protectively in front of his student. Naruto's lack of protesting told him how perplexed and nervous the young shinobi was. Otherwise the boy would have been outrageous for Kakashi trying to keep him out of the possible fight. The silver-haired man braced himself to encounter anything that could appear from the glow. He would protect his student, no matter what.

Then something raced out from the light.

It was… Kakashi narrowed his eye. It was a car, a deep red-colored vehicle. But it was nothing like the ones the shinobi had seen in Konoha. It looked almost futuristic. But before he could examine the vehicle further, the thing suddenly started shifting its shape, taking a completely new form.

Kakashi was sure he actually heard Naruto's jaw drop. The Copy Nin's dark grey eye widened as well as he stared at the thing in front of them. To say he had never seen anything like that would be a great understatement. He had never even imagined he would some day encounter something like this.

The stranger was huge. The red metallic form towered above them, the green glow reflecting from the sleek surface for a moment before the glow died out, leaving them in the dusk and gloom. Kakashi noticed the creature (he really had no words for to describe the thing in front of him) was vaguely human shaped, with long arms and legs and so on. But it looked like its form was made of car parts. There were cars in the Great Countries too, but not many and they were definitely not frequently used or seen. But this, this was something completely unfamiliar. The thing was also holding a spear-like item in his hand. Possibly a weapon, Kakashi's brain noted despite the situation. He was an elite ninja after all.

The stranger straightened himself and looked right at them.

Kakashi wasn't sure if he had imagined it, but for a moment he thought he'd seen a flash of surprise in the creature's eyes (it had eyes, weird eyes but eyes nonetheless). Kakashi decided he didn't like the look that followed.

The stranger said something in a language Kakashi had never heard before.

"Did it just talk? What did it say?" Naruto asked a little frantically behind him.

The metallic creature seemed to frown and took a step forward. Kakashi backed a little, holding a kunai in both hands and saying in a clear and commanding voice:

"Stay back!"

The stranger didn't seem too happy to hear his tone of voice. Kakashi backed off farther, pushing Naruto backwards too when the car-whatever-thing came closer, saying something in annoyed voice. With a flick of his wrist, Kakashi send a kunai right at the thing's grey-colored face.

The weapon scratched the strangers face just below the eye, leaving a long but shallow mark. Kakashi's earlier assumptions appeared to be correct when he heard a metallic noise when the kunai hit its target.

The stranger raised one long-fingered (though they looked more like knives to Kakashi) hand to its face and screamed something furiously. The spear in its hand flared into a bluish-glowing light. Then the thing was already storming towards them with impressive speed.

Kakashi and Naruto quickly leaped away to different directions. Naruto's eyes were full of fear and Kakashi admitted that it had been some time from the last fight that had actually made him scared too. But there was something utterly frightening in the whole unfamiliar and menacing situation so he really couldn't blame either of them.

Kakashi cursed his own weak state as the stranger tried to maul him, leaping quickly farther away. He was way too weak for a battle like this. He had practically no chakra, so he couldn't move half as fast as usually. If he had been able to use Raikiri, he might have had a chance against his opponent. But he only had his weapons, so he threw a second kunai, hoping to at least distract the enemy a little. The weapon bounced uselessly from the thing's chest, leaving only a scratch. But the stranger wasn't amused, and brought the spear down where Kakashi had been just second ago.

"Kakashi-sensei!"

Suddenly there was a roaring sound, and Kakashi saw a flash of yellow speeding towards the red metal-thing. The two collided with a deafening crash. Kakashi scrambled to his feet and Naruto was suddenly beside him, dragging him farther away from the battle before them. Kakashi realized there were now two strangers fighting against each other. The red one tried to hit the other one with the flaming blue staff, but the yellow creature that looked very much like the one who had attacked them easily dodged it, throwing instead a powerful punch right in the red's face.

The two ninjas were frozen to their places, enthralled by the battle of metal and steel before them. The yellow stranger seemed to be winning, kicking and punching and moving in a very agile way for such a big life form. The moves almost reminded him from taijutsu, and they sure were powerful. The red one was quickly losing, stumbling backwards and trying to keep the other one away with random sweeps of his spear. But with a final blow from the new stranger he was thrown to the ground, seemingly unable to get up.

Then the new stranger turned his attention to the two ninjas staring in awe. The creature took a few steps forwards.

Naruto had his hands on his teacher's shoulders and was hauling him backwards. The stranger halted, and for their surprise, held his hands in a universal "I'm not going to hurt you"-position. The creature let out a beeping, chirping sound.

"What did it say, Sensei?" Naruto's voice sounded a bit hysteric.

How the hell should I know? Kakashi thought, but kept staring at the thing, mind blank.

There was a pained groan and all the three glanced at the red one laying on the ground, without a doubt trying to get up. Their apparent savior turned back to them and beeped again almost urgently, then beckoned them to move closer. Then, while the shinobi stared in awe, the stranger transformed into a screaming yellow car.

The car's door opened invitingly.

Naruto drew a shuddering breath.

"Sensei, Sensei, what should we do?"

"I don't know Naruto…"

"Well, that thing did save us, didn't it?"

It sure looked like it, Kakashi thought. But he hadn't survived for almost two decades as a jounin with easily trusting strangers, especially creatures as strange as these. Just because they seemed helpful didn't mean they weren't up to something.

Kakashi weighted their options. They could try to fight the red thing again, but Kakashi was sure that the battle would not end well. Without chakra to enhance their movements and without any jutsus to use the fight would be over in no time, and not in their favor. And he didn't know how the yellow one would react if they declined its/his/her offer. They could also try to run, but they were in the middle of a desert with no chakra to boost their speed. If the strangers would follow them - as they without a doubt would - they would be hunted down.

And finally, they could accept the offer and see where it would take them.

The hostile stranger was standing up, muttering furiously and searching for his spear. The car's engines roared urgently.

"Naruto, get in."

Naruto turned his head so fast he could hear his neck crack. The boy stared at him. "Y-You sure? I mean –"

"NOW!"

The red creature was almost standing now, and Kakashi grabbed Naruto by the collar, shoving him towards the car. The blond kid crawled in, followed closely by Kakashi who seriously hoped he was making the right decision. He didn't want Naruto to suffer from his mistakes.

At the moment they were both inside, the car slammed the door shut and raced forwards. There was suddenly another green light appearing out of nowhere, not too far away from them. Kakashi glanced back through the rear window and was astonished to see a red car now giving them a chase. When he turned his gaze back forwards they were already diving into the green light.

Thank you so much for reading! Reviews and feedback will be more than welcomed!

AN: When I first thought about writing a crossover story with TF Prime and Naruto, the idea felt so weird I tried to abandon it right away. But the story kept pestering me, and suddenly I realized I already had an idea for the plot and a few scenes. And I was way too excited about the thought of writing a crossover (I absolutely love crossovers) to just abandon it. So, here it is, the first chapter of Will of Fire and Hearts of Steel!

This is my second fan fiction story. At first I thought I would be posting a few one-shots before this, mainly because I don't know how well I can write a multi-chapter story. But I just couldn't wait, and writing this chapter was so much fun I think I'll concentrate mainly on this now.

I'll try to update regularly, but I know I will have a busy spring so sometimes I just won't have time to update. So there will probably be some longer pauses between the chapters sometimes.

If you read this story and would like to read more, please let me know! I'm still not sure if this is a completely weird idea or not... But I had fun writing this and I'm very eager to continue!

And I haven't read much TF Prime fan fiction yet, so I'm not sure how well I can write one. But I'll do my best!

If there are any mistakes, please let me know so I'll fix them.