It was late at night in downtown Bellwood and an explosion sounded out at the bank as a large green creature resembling a rhino beetle and a cockroach crossed together with a large stinger on its rear and breast-like markings beneath its exoskeleton hissed out with a demonic green as it flew above the ground, flapping its insectoid wings when large pink crystals blasted by as the creature dropped its bags and looked beside it to see the Omni-Team standing there.

"Long time no see, Clancy," Hero Core said as Crystagirl changed back and the team stood at attention as Morphina cracked her knuckles with a sly grin and Lucky Girl looked to her.

"You guys ready for this?" Morphina asked. "Because I am!"

"Keep calm, cuz," Huntress said. "Clancy here's not a creature to be taken lightly. We need to go in with a plan of attack."

"I have a plan, Becks... attack!" Morphina shouted as she leaped up and transformed into Inferno and blasted a gust of flames at Clancy as he flew around her and blasted out a swarm of killer bees at her before she quickly morphed into Frostblight and froze them solid with her ice breath.

"Ha!" the ice fairy alien said as she morphed into VLOCT and started ramming into Clancy with several rapidfire shots before she slammed him back with her tail, sending him crashing to the floor as he aimed his stinger at her.

"Um, Jen?" Hero Core asked as his sister dodged the stinger with several quick moves and transformed back before morphing into her Anodite form and blasted Clancy with a huge mana laser, sending him unconscious and groaning in the ground as Jen morphed back and they all de-suited.

"Um, what was that?" Kevin asked, genuinely confused.

"What do you mean? I took down Clancy?" Jen asked.

"No, it's the way you did it," Gwen said. "I've never seen you this aggressive before. Not even at your worst moments?"

"Hey, what matters is the bad guy's defeated and we saved the day again."

"Yeah, I think you mean you saved the day again," Ally said with a glare as Jen sighed.

"Whatever. Let's go get some smoothies," she said, walking away before groaning as she felt her aching shoulder before shrugging it off as she walked to the nearest Mr. Smoothie.

"Something's seriously wrong here," Ben said as the others walked by her.

"No kidding," Ally said as she rubbed her arm. "It's not like Jen to fight on impulse just like that."

"Lately, it just seems like she's been a completely different person," Gwen ol the team. "And it's getting worse."

"Maybe she's trying out a new phase?" Kevin suggested.

"Jen would never do that," Becky said.

"Yeah," Ben said. "Not without consulting us first. Or at the very least just telling us."

"We've got to get to the bottom of this. Pronto," Ally said.

"No kidding. We have to help her."

"Maybe she doesn't want our help, though," Kevin sighed.

"You may be right. Though I seriously hope you're wrong."

The next day at Bellwood High, Jen sighed and ran her hair back through her hair as Ben and Becky walked up to her.

"Hey, can we talk?" Ben asked as Jen sighed.

"Sure."

"Lately it seems that you've been way more aggressive than usual. The way you've been battling our enemies, you've been sparing no mercy to them," Becky said.

"So?"

"So it's just completely unlike you to act that way to anyone unless they royally pissed you off," Ben said.

"And they did. Those guys messed up by attacking Bellwood, we had to take care of them."

"But you always give us a chance to get in on the action. Lately, it seems like you've been attacking without a game plan."

"Look, if you want a piece of the action, all you have to do is ask," Jen said with a groan as Ben and Becky took their seats.

"I never had to before. You just let me."

The teacher then walked up to the desk and wrote something down on the chalkboard.

"Okay, it's time for this year's science projects."

Everyone groaned in annoyance.

"And everyone gets a partner. First pair is the most obvious. The dynamic duo, Ben and Jen."

Suddenly, Jen groaned in annoyance and stood up with an angry look on her face.

"Why are we partners on every project? It's always Ben and Jen this. Ben and Jen that. It's never even Jen and Ben! News flash! We're not two heads on one body! We are two separate people who just so happened to be born on the same day! He's Ben and I'm Jen! We don't have to be viewed collectively!" Jen shouted. "We are two living breathing, independent individuals! From now on, think of me without Ben! Okay?!"

Everyone gasped in total shock at the pink-clothed girl and they all turned to Ben, who only gasped and shrunk down in his seat in embarrassment.

"Whatever this is, it's worse than we thought," Becky said to herself.

"No kidding," Justin said, whispering to her. "I've never seen Jen like this."

Jen stood in her room in the Tennyson household and groaned in slight pain as Ben walked in and gave a glare to her.

"What was that all about in class, Jen?" Ben asked her with a stern look as she stood up and faced him down, her eyes flashing pink. "I've never heard you talk about me or any of us like that."

"I'm going through some problems, alright," Jen said.

"Please just tell me this phase is almost over!" Ben said as Carl, Sandra and Emma looked from the hallway, obviously nervous as to what was going on between the twins.

"First of all, I'm sorry if I embarrassed you, but I meant what I said!" Jen said. "Second of all, this isn't a phase, this is real life! I am not doing this twin thing anymore, little brother!"

"Little brother?!" Ben asked in a shout. "Give me a break, Jen! Okay, so you're three minutes older than me. Big deal."

"Do you have any idea how long that is in girl's years?" Jen smirked. "Now I'm going on patrol. If you don't mind."

She walked out and the shocked family looked out and gasped.

"You were right, big brother," Emma said to Ben as she walked in. "Something is definitely wrong with her."

"And we're going to figure out what, Emma," Ben said, kneeling down and putting his hands on her shoulders. "I'm gonna make this right. It has to be me."

"You're going to fight your own twin sister?"

"If it means helping her, yes," Ben relented.

"I hope you know what you're doing," Carl said. "Just try not to hurt her too bad."

"Will do," Ben said as he fixed his jacket and walked away.

A few days later, Ally was working in the restaurant with Ben, Gwen, Becky and Kevin sitting at a table discussing what was going on with Jen.

"Something clearly happened to her," Gwen said. "It must have happened back at that warring planet last week."

"That's when this whole thing started," Becky agreed.

"Oh man. It's got to be the quill that Argit accidentally hit her with," Kevin said.

"What?"

"I don't know. It must have altered her personality or something. I'll contact Max about this and we'll see what we can do," Kevin said.

"No need. I'll knock some sense into her," Ben said. "She's my sister. I know all of her moves and every ability she has inside and out. If anyone has the ability to take her down, it's me."

"Yeah, but she knows all of your aliens and all of your moves too," Gwen said. You're evenly matched."

"Don't worry. We've spent once a week sparring against each other constantly. We figured that something like this might happen to one of us or if Albedo and Alexia aever returned. We both know that in that situation, one of us would have to take down the other, so we practiced."

"You knew?" Kevin asked.

"Doesn't something like this happen to every twin superhero team?"

"He's got a point," Ally said walking over. "It was bound to happen sooner or later."

That was when the doors to the front door opened and everybody gasped as they saw the girl who walked through, jaws on the ground. Especially Ben an dAlly.

Jen was wearing a black leather jacket with long black boots and sunglasses on over her pink shirt as she waled up to a table and sat down, putting her feet up on the table.

"Be right back," Ally said as Maggie walked over to Jen's table and took her order, giving out a groan.

"May I take your order, Jen?"

"I'll grab a plate of hot wings," Jen said. "On the double."

"Um... sure. Anything to drink?"

"Root beer."

"Coming right up..." Maggie said as she glared as her irises flashed black and Jen felt a sudden tug and stumbled back in her seat as she looked at the shadow she was casting and groaned.

"Okay, maybe now I have to help her," Ben said as Gwen stuck her left wrist out and her watch sent a small microscopic tracking device that attacked itself to Jen's jacket as Ben nodded and walked away as they left and went towards Omni-Manor to prepare Ben for his fight.

Two hours later and three plates of hot wings later, Maggie walked up to Jen and rose a hand as a shadow from the table formed a tendril and swept her feet off before she slammed the check on the table.

"Your check," she said as Jen scoffed.

"What about my other order of hot wings?"

"Forget it," Maggie said, crossing her arms. "Pay up and get out."

"What?! Give me one good reason why I should leave!"

"How about... eight reasons?" Maggie asked, counting off on her fingers. "Your car is illegally parked, your feet were on the table, your mood, you're rude, you're crude, the way you eat your food, bad attitude. Oh, and the biggest reason of all: you've been treating all of your friends and your own brother like crap lately. The only Jen I want to see in this restaurant again is the one who we all love."

"Oh, yeah?" Jen asked, fixing her jacket. "Fine. I'll leave. I've got some crimes to stop anyway."

"Yeah," Maggie said to herself as she left. "But your brother's going to have to stop your crimes."

Soon enough, Ben as Stinkfly flew through the sky and his Omnitrix symbol started beeping.

"Careful, Ben," Gwen said. "Your sister's a real tough cookie. No one knows that better than you."

"I'll keep that in mind," Ben said as he looked at the tracking device in his hands and saw tons of criminals hanging from vines that were hooked up to streetlights.

"She must have used Wildvine or Blossom Rose to stop these guys. Looks like I'm on the right track."

This game of cat and mouse continued for about an hour with Ben having to stop to rest every few minutes until he saw Jen cornering a criminal on a rooftop.

"No one come's to Bellwood and gets away with crimes when I'm in town."

Unfortunately, Jen was blasted with a slime ball that hit her as she turned around and saw her brother touch down with a glare towards her as she sighed and used her telekinesis to take the slime off the jacket as the criminal snuck away down the fire escape.

"Dude, this is rich Corinthian leather!"

"No charge. Now you need to be taught a lesson, Jen."

"From you?" Jen asked as lightning started to crack and boom across the sky. "Give me a break. We were always partners, but you kknow I would win if we ever fought."

"Not on your life."

"Hey, I'm just as responsible for the team as you are! If you didn't have me, you would never have been able to save the universe!"

"The same goes for you! You've been unfit to be a leader lately!" Ben shouted as it started to drizzle around before becoming a full downpour as he paced the ground as sister only looked sternly to brother. "You're impatient! And hot tempered! And most importantly, at this moment... I'm better than you."

Jen only laughed at that before growing serious. "You know something, little brother? I have to disagree with you on that one."

The female twin pressed the button on her Omnitrix and was instantly coated in her Omni-Suit.

"I'm done being your partner. I'm a solo act now!"

Ben sighed and pressed his button, being coated in his Omni-Suit as they stared at each other through their visors.

"I don't want to fight you, Jen," Ben said as Jen glared hatefully at him.

"I wouldn't want to fight me neither," she shot back as she blasted mana ray after mana ray that he blocked with a green shield from his gauntlet as he crouched down towards his sister.

"Then I'm sorry, sis. But I'm going to help you. Even if I have to beat all the sense into you as I have to!"

They both shouted out as a flash of green and pink light appeared and Swampfire blasted out tons of fire blasts towards Jen's pink Goop form as she dodged around it and slimed her brother before she morphed into Wildcat and snarled as she sliced him to ribbons with her claws, roaring fiercely.

Swampfire reformed and transformed into Wildmutt and the dog and cat aliens both roared out as they slammed into each other and started to wrestle, scratching, clawing and biting each other all they could as the rest of the Omni-Team stood by in horror.

"Oh my God," Justin said as Julie started to form a tear in her eye.

"What if Ben can't snap Jen out of it?" Julie asked. "Either the love of my life will destroy his own sister... or she'll destroy him. How could this get worse?"

"Is there anything we should do?" Gwen asked, hair drooping in the rain.

"I'm not sure there's anything we can do," Ally said.

"We'd better sit this one out," Becky agreed as the cat and dog fight continued below.

Wildcat roared and scratched at Wildmutt as he rolled onto his back and kicked him off off her with his powerful hind legs before he roared and transformed into Discharge and blasted her wiht lightning, causing her to yowl in pain as she transformed into...

"Sound Wave!" the Sonorosian shouted as she replicated and let loose a powerful scream.

Discharge groaned and held his ears in pain as he hit his symbol and transformed into...

"Rockstar!"

He let loose a powerful green ffist from his guitar that slammed into all of the Sound Wave clones as they were sent flying away as they merged back together and morphed into Stinkbomb and let loose a cloud of powerful fumes from her posterior towards her brother as Rockstar adjusted the tuneage on his guitar and jammed out a fire blast that ignited all the toxic fumes around her, sending her flying to the next building and Stinkbomb groaned.

She stood up before she was wrapped in tons of bandages and saw Snare-Oh wrap his way around her entire body.

"Had enough?"

"Funny, bro. I was about to ask you the same thing!"

She immediately transformed into Inferno and the flames that made up her body caused Snare-Oh to back up from her and he transformed into Diamondhead and sent tons of crystals at her as they pierced through her flames and sent her crashing into the fire escape door.

"Ooh, that's gonna leave a mark."

"Me...du..sa..." Inferno gasped out as the serpentine alien hissed out and dodged all the crystals, slithering around the body as she grasped her brothers arms and stared into him as her eyes glowed yellow and Diamondhead smirked as he grabbed her throat and threw her back.

"I don't get it," she hissed. "You were sssupposssed to turn to ssstone..."

"Yeah, kind of hard to do that when I'm already made of crystal."

Jen shouted out as she transformed into Four Arms and the twins started sparring hard as Diamondhead took a cheap shot and slammed her with a pillar of crystal from the ground as the Tetramand sent a rock wave out with a slam on the ground that Diamondhead instantly bore through with a shout of effort.

"Okay, you're just as good a fighter as I am. But I know the one thing you won't be happy to see," Four Arms said as she slammed the Omnitrix symbol on her chest and turned back to normal before she shouted out as her form instantly shifted to her Anodite form... and then to her Master Spark form as she hovered in the air.

"That girl is out of her mind!" Gwen shouted.

"Exactly. But Ben can beat her," Kevin said.

"I knew you were gonna do that,' Diamondhead said as he leaped off the building, slammed the Omnitrix symbol and transformed into...

"Way Big!"

Jen shouted out and blasted her To'kustar brother with her mana fireballs from all sides that sent him stumbling back as he swatted her down as she morphed her body into mana before reforming, just as she was smashed into a wall with her brother's fist as she smiled.

"There he is."

She thrust her hands apart as her four elemental crystals formed around her and she spun them around her, slamming them into Way Big as he shouted out as they blasted fire, ice, earth and lightning beams that sent him stumbling back before he countered them with his own cosmic ray by crossing his hands, cancelling each other out as Jen suddenly encased herself in a mana force field to keep the debris from hurting her... only for her brother to grab her and squeeze her, bringing her up to his face.

"Sorry, Jen," Way Big said. "But I have to do this."

He then tossed his powerful sister into the ground, forming a crater beneath her that instantly had her transform back to normal... and then a black quill came shooting out of her shoulder before coming to rest on the street next to her.

"Ooh, that's gonna leave a mark," Ally said as Gwen created a mana platform that she levitated them all down from as Becky walked over to Ben, who transformed back and looked down to see his sister as she groaned in pain.

"Sorry about that, sis. But you had it coming for the past two weeks."

"Forgive and forget," she chuckled before he fell unconscious.

That was when Verdona appeared in a flash of pink light.

"There there, Jennifer," she said, brushing her granddaughter's hair back and picking her up bridal style. "I'll take care of you and you'll be right as rain."

"Ugh," Jen groaned as she came to back in Omni Manor as her grandmother finished healing her from the extreme fight with her brother and the quill that had been stuck in her for a week coming out.

"You okay, sis?" Ben asked as Jen looked around to see all her friends and family there.

"Wh-what happened? Where am I?" She looked down to see her black leather jacket and shuddered in disgust. "And what am I wearing?!"

She took off the jacket and then snapped her fingers and her attire instantly changed back to normal.

"That's better," she said as she hung the jacket on a rack as Ally smiled.

"I don't know. I think that jacket actually looks pretty good on you," she chuckled.

"You're only saying that because you're a goth," Gwen said.

"Touche. So, do you remember what you said to us over the past week?"

"Unfortunately, Ally... yeah. It's all starting to come back to me."

"Argit's quill that lodged itself in your shoulder must have altered your personality," Max said as Jen walked over to her chair and sat down. "It must have brought the worst parts of it to the surface."

"It can do that?" Ben asked.

"Rarely, but yeah," Kevin said as Becky sighed.

"That rat's going to be toast next time I see him."

"Now that I think about it, I guess those feelings must have been somewhere in the back of my mind," Jen said. "But I'm truly sorry for it. I hope you're not mad at me for fighting you like that, Ben."

"Of course, I'm mad at you, Jen," Ben said, laying a hand on her shoulder. "But I also know you weren't yourself during that whole spiel. So I forgive you."

"Thanks."

The twins then smiled and hugged each other hard, much to everyone's joy.

"Don't forget me," Emma said as she struggled and created a tiny mana platform beneath her feet as she hugged her brother and sister.

"Glad that's over," Gwen said, nudging Becky.

"I think that Jen might have to kill Argit before you do," Ally said to Becky.

Outside Omni-Manor, on an adjacent rooftop, the Scarlet Warrior looked on before a sudden fwoosh sounded by her and the woman sighed as she turned around.

"What do you want, Drake? Don't you have other places in the multiverse to be?"

"Not really," Drake Flame said, pacing by her. "I'm just here to give you a warning. You may be the Omni-Twins' guardian, Scarlet Warrior. But one day soon, that's not all you'll be. Ben and Jen Tennyson will need some of the best training in the multiverse to get through their upcoming ordeal. And it seems like you'll be the one to train them how to fight at your level."

"Really?" Scarlett asked, drawing her sword on the Alpha Osmosian.

"That is all I can reveal at this time, milady," Drake said with a bow. "Ta."

He then teleported away in a puff of black smoke, leaving a very confused Scarlett as she looked back down at Omni-Manor.

A/N: Yeah, I know. Not my best work, but it's hard to come up with new original things. Especially for something with a concept like this.

Next time on Ben and Jen 10:

Vreedle, Vreedle