My first Ben 10 and Young Justice crossover. I hope you enjoy. I was inspired by other stories so there might be some similarities. Takes place after series 1 he's 13 years old and ever gave up the Omnitrix.

Enjoy!

Ben, Gwen and their Grandpa Max were currently fighting Hex and Charmcaster. They were in the forests of Salem in Massachusetts.

Apparently Hex wanted to resurrect the spirits of bunch of witches. Then use their power to take over the world or something. Honestly Ben stopped paying attention in the first two seconds of his monologue.

While Hex was casting a spell Charmcaster was holding them off. "Hero time." Ben said slamming the Omnitrix.

"Ditto? I wanted Fourarms." He said to the Omnitrix upset. But decided he had to make the most of it. So Ben hopped on a tree then multiplied and jumped off of a branch.

Ditto prime distracted Charmcaster so that Ditto clone took her bag of tricks. "Hey." She whined then was shocked unconscious by Grandpa Max.

"This goes great with my outfit." Ditto clone said while putting it on then Ditto prime replied. "Yeah really brings out your eyes."

"Hey doofuses fashion later. Hero now!" Gwen shouted while blocking one of Hex's spell's with great difficulty.

"Relax." Ditto prime said then an army of Ditto's suddenly dog piled on Hex. "See all part of the plan." Ditto prime said high fiving his clone.

"Yeah nobody in the Universe can beat us." Ditto clone said as he tossed away the bag. Then Hex who was able to break free of the other Ditto's was about to continue the spell when a portal opened by behind Ditto prime and clone.

This distracted Hex because he didn't activate any kind of teleportation spell. But his confusion didn't last long as he was knocked out by Gwen who did a round house kick.

The portal then started sucking the two Ditto's in who were flailing their arms in a panic. Ditto clone then pushed off from prime and went into the portal.

The portal then closed and a beeping was heard signifying the Omnitrix timing out. And when it did the other Ditto disappeared and Ben stared wide eye at where the portal had been. "Woah what happened?" He said wondering what happened to the clone.

With the clone (Won't refer to him as clone anymore)

Ben was going through a vortex for a while now. At first he was panicking like crazy but after a while he just let himself float which was almost relaxing.

While he was doing that he was tinkering with the Omnitrix seeing if maybe he could contact Azmuth or something.

After about a half an hour something did happen. The dial lit up and the silhouettes started changing rapidly. Ben smirked when he repeated what he did that first summer. "Sweet!" He cheered.

Ben then saw a portal and smiled finding a way out. "Awesome." He cheered but then found himself being rapidly sucked into it. "Not awesome." He shouted fearfully.

Ben screamed as he went through it then slammed the Omnitrix hoping luck was on his side.

YJ Universe, Happy Harbor

When Ben came out of the portal as Cannonbolt and saw the aftermath of a battle. Then he saw five people not too far from him.

"Fine then, I won't deny you children have power." Ben heard a Robot say. "But, playing hide and seek won't help me achieve my objectives. So stay concealed and if you stand in my way again. I will show no mercy." He finished.

Ben quickly figured out that he was the bad guy. "Hey tin man!" Ben shouted getting his attention.

"Pick on someone your own size." Ben added the robot merely stared at him. "What are you supposed to be precisely. I have no records of you in my data banks."

"Pardon me." Ben said giving a mock bow then said. "You can call me Cannonbolt." He added then curled himself up into a ball. "And I'll call you road kill!"

Ben rolled at the robot who merely moved to the side to avoid it. "I grow bored of this." He said but didn't see Ben bounce off a car and hit him in the back.

"Really cause I'm having a ball." Ben quipped as he landed then launched himself at the robot again.

The robot then generated a tornado pushing Ben back into a pile of rubble. "Well that didn't tickle." Ben said as he rubbed his head while getting up.

Ben noticed a couple of small tornado's around him and guessed that was his power. "Who is this guy?" Ben thought out loud.

"You may call me Mister Twister. Now disappear as those children did." Twister said as he deactivated the twisters and started to leave.

"What are you talking about they're over..." Ben trailed off as he saw that the five teens were all gone. "There?"

As twister was leaving Ben decided to try the feature he re-unlocked and change into a new alien. The bright green flash caught Twister's attention.

He turned around to see it only to be kicked rapidly. When he recovered he saw Ben as a black and blue velociraptor like creature with spheres on his feet.

"Gotta be quicker than that." Ben said as he lifted his visor up.

"Another speedster?" Twister questioned not reconizing Ben then saw the same insignia on XLR8's chest that Cannonbolt had on his forehead.

"I see. So you're a shapeshifter. Though you don't appear to be Martian." Mister Twister analyzed.

"How are you capable of such advanced transformations?" Twister questioned wanting to know more.

"Because I'm human not a Martian and it's the Omnitrix." Ben explained then ran at him.

But Twister was ready and created another small tornado to push Ben back. "You are out of your league Omnitrix. And I am out of patience." He said.

Then like he did before Mister Twister reeled back and unleashed two giant twin cyclones causing a massive storm to be generated above him forming thunder and lighting flashes in the sky.

"This should cease any possibilites of you defeating me." He said then unleashed a powerful lightning bolt shot at Ben who attempted to change aliens.

As the smoke cleared Twister examined the ground to find nothing. "Finally. It was about time I finished off these meddling children." He said.

Then Ben as Ghostfreak emerged from the ground behind Twister. "Better check your watch tin man." Ben said catching his attention.

"Because mine says it's Hero Time!" Ben exclaimed as he advanced.

"How is that possible?" He asked and even in his robotic monotone voice anyone could tell he was surprised.

"What's the matter? You've never seen a Ghost..freak." Ben quipped with a creepy chuckle.

As Ben advanced Mister Twister created another twister but it had no effect. "Your trick is nice. But let me show you mine." Ben told him. "Now you see me." He continued as his body started to vanish. "Now you don't."

Like many other's would Twister looked around hoping to find him. But unlike others he was prepared. He turned around and sprayed some type of orange sludge.

Ben then suddenly reappeared then Twister grabbed him and held him up. "I have come prepared with multiple contingencies to stop the one I am really after." He said tightening his grip.

"Although I must say you have surprised me which is why I'll warn you one last time." He added.

"Stay away. Do you understand?" He stated pulling him closer for emphasis.

There was another bright green flash and Ghostfreak was replaced by a green crystal like golem.

Diamondhead formed a blade with his arm and stabbed Twister in stomach. "Crystal clear." Ben replied with a smirk then cut the rest of his upper body in half.

Twister's body then just collapsed onto the ground. Ben grabbed the scarf twister had and held it. "I guess I have my first souvenir from...wherever I am." Ben said.

As he looked around he could tell he wasn't at least on another planet. "Might as well look around." Ben said as he changed form.

Soon there was another green flash and he became a green bug like creature with four eyes. "Stinkfly? I wanted XLR8 guess this'll do" Ben said before he took off into the sky.

As Ben was only flew for a few seconds his head hit something. "Ow. What was that?" He asked then felt some type of object that was invisible mid air.

"This must be what mime is like." The bug like alien joked as he pretended to be one. "What is this thing?" Ben questioned then felt what appeared to be a wing.

"Weird." Ben said then he heard an all to familiar sound of the Omnitrix timing out. "Aw..." Stinkfly started to say but timed out before he could finish. "Man." Ben now in his human form finished.

Ben then tried to grab onto the invisible object but lost his grip. He screamed for a few seconds before he felt himself stop. "What the?" He said as he was floating like it was Zero gravity.

"I got you don't worry." Ben heard and he then saw the same girl as before. "Thanks I owe ya one." He replied.

She smiled before saying. "Well since you saved me and my friends let's call it even."

Ben returned the simle then looked over his current situation. "Uh this is cool and all but can I get down now please?" Ben requested.

"Hello Megan. Sorry." She replied slapping her forehead and gently lowered Ben on the ground.

"So your name is Megan huh. My name is Ben." Ben said and she replied with. "It's a pleasure to meet you. But actually my name M'gann but Megan is my earth name and I'm on earth now."

"So where ya from Mars or something?" Ben asked slightly as a joke.

"Yes." M'gann said nonchalantly.

Before Ben could ask anymore questions the other four woke and were quickly alert. "Where is he?!" A kid with a red S on his shirt yelled.

"Yeah I wanna turn Twister into a toaster." A kid with red hair asked.

Ben then decided to speak up. "If you're talking about the robot tornado thingy his spare parts are over there." Ben said gesturing to Twister's remains.

"Who defeated him while we were all unconscious?" Aqualad questioned.

"I wasn't unconscious but-." M'gann started to say but before she did the speedster ran over to her and put an arm over her shoulder's.

"I knew my Megalicious could do it." He said with a flirtatious smile.

"It wasn't me it was Ben." She said correcting him and ignoring his attempts to flirt with her.

"Who?" Kid Flash asked.

"The only other super hero here." Ben told them gaining their attention.

"You took him down?" A kid with a pair of sun glasses asked.

"No way." The red head said.

"I saw the whole thing." M'gann said.

"You don't look like much." The kid with the S on his shirt said.

Ben then slammed the Omnitrix dial and turned into Fourarms. "How about now?" Fourarms asked with a confident smirk. The reply was just several nods then Ben transformed back.

"Names Ben 10." Ben introduced himself.

"That's what you call yourself really?" The red head asked.

"Probably better then what you're called." Was Ben's reply. "Which is what again?" He asked.

"We have been rude I am Aqualad but you may call me Kaldur'ahm. You've already met Miss Martian." The Atlantean introduced.

"I'm Robin and that's Kid Flash." Robin said pointing to him and Wally.

"Kid Flash really? What do you do turn on the lights?" Ben joked earning a laugh from Robin who put a hand on his shoulder and said. "I like you already."

"So who's Mister personality over here?" Ben asked and the brooding Kryptonian replied simply. "Superboy."

"Ok then. Well later." Ben said then started to leave only to stop when the speedster blocked his path. "Where do you think you're going?"

"Find some bad guy's, beat em up then get a smoothie. You know usual hero stuff." Ben said like it was no big deal.

"Sorry but we gotta bring you to the League first. Otherwise Bat's will have our heads." Robin said.

"Take me to what then who now?" Ben said confused.

"You know Justice League earth's greatest Hero's. And Batman the scariest guy on the planet." Kid Flash told him.

"Never heard of them dude. Also I'm earth's greatest Hero. I mean I saved it and the universe like a hundred times at least." Ben said.

The five teenagers looked at each other in confusion since none of them ever heard of him. And the League kept tabs on multiple other hero's.

"I don't believe you." Kid Flash said looking at Ben suspiciously. "And you're approval is important because?" Ben rhetorically asked.

"Look if guys need to take me to your babysitter's give me one good reason why I should go without a fight?" Ben asked.

"You get to ride in the Bioship." M'gann told him decamouflaging it shocking Ben. "Ok I'm in." He stated eagerly then walked towards it.

"Good thinking babe." Wally commented.

"Indeed." Aqualad added then asked. "But how did you he would agree simply by showing him the vessel?"

"Well I didn't read his mind but I could feel his adventurous nature. And when I told him I was from Mars his curiosity peeked." She explained to them.

Before they could ask anything else Ben called out. "Hey we gonna go or what?" He asked standing on the ramp of the ship.

Soon they boarded and headed toward Mount Justice.

Inside the Bioship

"So this thing is really organic like alive? Plus it's psychic?" Ben asked continously poking the wall. "It is and it reacts to my mental thoughts." M'gann answered.

"Cool." Ben said not stopping his poking.

"Thank you. But she would appreciate it if you to stopped poking her." She told him and Ben stopped immediately. "Sorry." Then rubbed where he poked as an apology.

"Huh I figured you'd be used to riding space ship." Kid Flash commented.

"I am. But this one of the few times that I've been on that I don't have to break out from or destroy." Ben said still looking around.

"So what's your story?" Robin asked.

"Huh?" Ben replied confused.

"What Robin means to say is how did you acquire your transformation ability and where are you from?" Aqualad rephrased.

"Long story." Ben said.

"Give us a short version then." Superboy suggested.

Ben then sighed then listed some stuff that would hopefully satisfy their curiosity. "Got this watch when I was ten after it fell from space, been a hero for like three years now, from another dimension, and I'm a clone." Ben told them casually.

The result was completely opposite. They all looked at Ben in shock. But the most surprised reaction was from Superboy who looked at Ben in disbelief.

"Another dimension that's awesome. Is there another Kid Flash? Am I as handsome as I am here? Wally asked.

"Nope. In fact I think I'm the only hero on my earth." Ben said.

"How'd you get here?" Robin asked.

Ben then explained. "I was fighting this guy named Hex who was doing some weird magic stuff." Ben started.

Kid Flash then scoffed at that. "Magic yeah right." He said quitely but everyone heard him.

Ben then continued. "Then some portal thingy opened up and I was sucked in."

"Who cloned you?" Superboy asked curiously.

"One of my aliens called Ditto which can clone himself did. I got sucked in to make sure the original me didn't." Ben informed them then asked. "Why?"

Superboy didn't speak but unfortunately the speedster did. "Supey here is clone too using Superman's DNA." He informed.

"Sweet welcome to the club." Ben said then put his hand up for a fist bump which Superboy ignored. "Okay then." Ben said retracting his hand.

Later in Mount Justice

"Welcome to our home." M'gann said as they stepped off the Bioship.

"So you have a secret base in a mountain." Ben commented looking around with a smile. "Not too shabby." He continued.

Kid Flash taking this as an insult then asked. "Well where's yours?"

"That depends there's one in Mt. Rushmore, under my home town even my future one in space." Ben listed off dumbfounding the yellow speedster.

"You've been to the future?" Robin asked intrigued.

"Future, dimensions and sometimes a bit of both." Ben replied.

"Dude hard core!" Robin said then the two high fived.

They then headed toward the meeting area where Batman instructed them to bring Ben. "So who's this big bad bat dude you guys mentioned." He asked while he walked backwards but noticed stopped and so did he.

"This him?" A voice asked behind Ben. "Yup this is him." Robin replied.

Ben turned around and looked at a man with some type of Bat costume on. And behind him several other's who Ben guessed were this dimension's Hero's.

As Batman was about to speak something that surprised almost everyone happened. Ben started to laugh really hard.

This was shocking because most people who even glance at the Dark Knight are usually afraid of him. The only one who ever had a reaction like Ben's was the Joker.

After a few minutes though Ben finally stopped. "Sorry dude it's just you look like you put your underwear on wrong." He said.

That comment caused Kid Flash, Robin to start laughing hysterically since they never thought about it until now. Even some of the less mature Leaguers in the room laughed a bit but quickly composed themselves.

"Start talking." Batman demanded in an aggressive tone.

"You forgot to say please." Ben replied with a smirk. Batman's eye's only narrowed which only Robin knew that meant he was getting annoyed.

Ben then sighed. "Okay but it's a long story." He told him then Martian Manhunter walked over. "Maybe I could be of assistance."

Ben looked at hin curiously and shrugged his shoulders. "Ah sure whatever man." He said.

Then the Martians eyes glowed green as he concentrated. Ben suspected something was going on but after a few minutes he got bored.

"Um is something gonna happen?" Ben asked to which the Dark Knight replied. "You don't feel anything happening?"

"Feel what?" Ben questioned confused then Manhunter's eye's stopped glowing signaling he stopped. But when he did he hunched forward and began to breathe heavily as if he ran a marathon.

"What just happened?" Ben asked afraid he did something.

"Did you get anything?" Batman asked but he had a hunch he didn't.

Manhunter shook his head as his breathing returned to normal. "Nothing. Something is preventing me from reading his mind."

Ben's eyes widened. "You were trying to read my mind? That is so cool and even cooler I stopped it." Ben said with excitement.

"You mean you stopped a Martian from reading your mind without even trying?" Kid Flash asked in shock.

"Jealous?" Ben replied with a smirk.

"Start talking." Batman demanded once more.

"Sure. But can I get a smoothie first." Ben asked.

Later

"And that's whem I showed up kicked some robo butt." Ben said finishing his story while drinking his seventh smoothie.

Ben had just finished explaining everything the run down version of his life story. From the summer he got his Omnitrix to how he got here.

To say they were surprised would be an understatement.

"So the device on your wrist allows you to transform into multiple different allien species from your world?" Batman questioned and even though he didn't show it he was worried about that kind of power being possessed by a young child.

"Yup just push the button, turn the dial, and boom I'm one of a bunch of super cool alien dudes." Ben said showing how he normally does it. (But without actually transforming)

"Awesome." Captain Marvel said who then recieved looks from othe member's. "What? It is." He responded.

"Thanks man." Ben said sipping the rest of his smoothie.

"In that case Ben we're going to have to ask you to hand it over." Batman said.

This caused Ben to choke on his smoothie and after coughing a bit he replied. "Sorry what was that?" He asked not believing what he just heard.

"We need you to hand it over." Batman said again.

Wonder Woman then stepped in. "Batman don't you think you're overreacting?" She questioned.

"Imagine if someone like Lex Luthor had a device like this? You know I'm right." Batman reasoned.

"Maybe we should listen yo him on this. If Lex had this then-." Superman started to say.

Before they could argue any further Ben gave them some new knowledge. "Sorry to interrupt but just letting you know it won't come off."

"Yes it will." Batman said.

"No it literally won't come off it's latched onto my DNA. As in only I can use it or take it off. And still don't know how this thing really works." Ben informed them.

"Can't be that hard let me." Captain Marvel said as he walked and started to pull on it.

"I wouldn't do that." Ben warned.

"What's the worst that could happen?" Captain Marvel asked ignorantly as he pulled tighter.

"Never say that." Ben told him then the Omnitrix started to glow and a bright green pulse was sent out. Sending Marvel flying into a wall and causing the others to be pushed back several feet.

"Told ya so." Ben said.

"What was that?!" Superboy shouted at Ben who told him. "Security feature. Activates whenever someone without the proper authority tries to take off the Omnitrix."

"Why didn't you tell us there was a security feature?" Kid Flash asked.

"Hello most powerful device in the universe. It seemed kinda obvious." Ben replied.

As the rest of the Team and League recovered Batman requested they meet in the Watchtower to discuss what to do with Ben.

When they left Ben looked around and asked them. "Where's the food because I'm starving."

"This way I'll show you." M'gann replied leading him to the Kitchen.

"Dude how can you be Hungry after drinking that many smoothies?" Wally asked.

"It haven't had breakfast yet plus I skipped dinner last night. It was just too gross to eat." Ben informed them while shuddering at the memory.

Soon enough Ben was eating a sandwhich retelling one of his adventures. "So what did you first transform into?" Robin asked curiously.

"This Alien made entirely out of fire. I call him Heatblast." Ben told him before taking another bite. "I freaked out at first but then it was really cool or should I say hot." Ben continued then chuckled at his own pun.

"The only downside was I started a forest fire." Ben informed them shamefully. This comment caused the speedster to laugh.

"What are laughing at. First time I saw you use your powers you ran into a wall." Robin reminded him shutting him up and causing Ben to laugh.

"What powers it Kryptonite?" Superboy asked seeing it was green when it was fully charged.

"Not sure exactly. But I know it runs on self sustaining energy. But after a while it has to recharge." Ben told them grabbing a bag of chips still being hungry.

"So you can't stay in the form you want for long." M'gann said while mixing ingredients for another batch of cookies.

"It used to be about only fifteen minutes more or less and I could only be one alien at a time." Ben informed them.

"How long is it now?" Aqualad questioned.

"I unlocked this feature where I can swap my aliens. But for how long not sure." Ben said looking down at the Omnitrix.

Just then they heard the Zeta tubes activate "Access Batman." Then the Dark knight came in and the Team plus Ben went over to him.

"So Mr. Tall, dark, and spooky what's your verdict on Ben 10? Hero or number 1 on your wanted list?" Ben asked in a joking manner but planned to fight his way out if necessary.

Batman just kept his glare and replied. "The League has decided that you for the time being at least should remain here."

Ben raised an eywbrow at that statement before continuing. "As your prisoner or-?"

"As part of the new covert ops team the League has created." Batman corrected.

Ben thought about it for a second then smiled. "Oh I get it. This way you can keep an eye on me to see if I am a threat or not without looking like the bad guy." Ben stated.

The only ones who weren't at least a little surprised by this were Batman and the Boy Wonder.

Before Batman could deny or confirm that Ben shrugged and said. "I get it so sure why not. Just don't do one of those things where you get somebody to be my friend just to spy on me. Deal?"

Batman merely nodded then looked over to Robin and told him to show Ben his room.

"Well now that that's done." Wally said then took out the robotic eye he collected as a souvenir. "Gonna put this in my new trophy case."

"Same here." Ben added holding up his souvenir. But unbeknownst to them someone was watching them through the eye.

Unknown Location

In room filled with the same screens Dr. Desmond used to contact the Light, they themselves began conversing about what had transpired as of late.

"Interesting a device capable of giving the user transformation abilities." A male voice stated.

"Should a weapon of a caliber such as that come under our control it would accelerate our plans indefinitely." A feminine voice pointed out.

"Did we obatain sufficient data in that first encounter?" Another male voice asked.

Flashback

While Ben was trapped in Twister's clutches he took the opportunity to attach a cord on the Omnitrix.

It soon started to download data but it was cut short when Ben destroyed the android.

Flashback over

"A good amount to begin researching but not enough to reengineer it. We would've obtained more but the device as we have seen has a self defence feature." Was the reply.

"Do not worry yourselves in time we will see him again. But for now darkness must conceal our light." The one who appeared to be the leader finished.

So what did you think. I worked really hard on it. I'm open to suggestions if you have any. Please review.