I started to write one-shot ideas as well. I have ideas in my head that I'll probably and/or definitely won't make into stories. So here one idea I wanted to write and for you guys to check it out. Also, remember I don't own any of the franchises in this one-shot only the OC that will appear.

"Natsu, I'll fight Lucy and Night Rogue, you fight Gajeel!" Jacen told him.

"But, Jacen…" Natsu tries to say something.

"Don't worry, I'll save Lucy," Jacen says, as took out the Lock and Dragon Fullbottles and placed them in his Build Driver.

DRAGON! LOCK! BEST MATCH!

He started to crack the lever creating pipes and support suddenly came out of the Driver, forming the Snap Ride Builder, both gold and blue halves of the armor standing on each side of Jacen.

ARE YOU READY?

"Henshin!" He shouted.

Jacen gets smashed between both half-armor that closed on him. Then both halves now forming a single full body armor. Turning him into Kamen Rider Build KeyDragon Form.

FŪIN NO FANTASY STAR! KEYDRAGON! YEAHHH!

"The rules of victory have been set!" Jacen declares. Before running towards the Stretch Smash known as Lucy.

Jacen goes out to punch the Stretch Smash trying to defeat it so he can absorb the Nebula Gas from her.

Natsu was trying to fight Gajeel but he was too distracted on Lucy. She was tortured to become a Smash just like Lisanna.

When he was fourteen, he and Lisanna were kidnapped by Night Rogue and Blood Stark and experimented on, Lisanna was turned into a Burned Smash while he was still in the lab being studied by Blood Stark. They were lucky Jacen and the others found them and saved them. When Jacen purified Lisanna's Bottle it became the Dragon Fullbottle., nobody knows if it was a coincidence or it was Lisanna close relationship with Natsu, but Jacen gave it to him after being convinced by Cana to let the two keep their connection.

He knows Blood Stalk helped Night Rogue turned Lucy into a Smash, just like he made Elfman go on the rampage that caused the death of Lisanna. Natsu thoughts were interrupted when he sent flying when Gajeel gave him a hard punch in the face.

"Natsu! You okay?" Macao crouch next to him.

"Yeah, just a bit distracted," Natsu cough.

"Natsu," Elfman getting their attention. "I know, seeing Lucy as a Smash is reminding how they made Lisanna into a Smash too, but you can't let that distract you right now! We need to save Lucy!"

"He's right, Natsu, Jacen will get her back to normal," Cana reassured him.

Natsu smiled but frowned when he heard Jacen grunts of pain. The mages see Jacen being burnt by blue flames. He still tries to fight and dodge the Smash, it was no use when Lucy headbutted him making him de-henshin and roll down on the floor.

"Jay!" Cana shouted in worry running to his side. "Are you okay?"

"The Dragon Fullbottle is still too much for me," Jacen says.

"It looks like you are in no condition to fight anymore. Be good and hand me those bottles," Night Rogue says, as walks towards him.

"Like hell, you are," Cana growls, as she brought out to cards, but before she can use them on him, she was grabbed from behind. "Ah!" She saw it was Lucy. "Lucy! Let go! You have to remember!" She tried to get through the Stretch Smash. Only for her words fell deaf ears and thrown by her fellow guildmate.

"While she's out of the way, how about you give me those Fullbottles," Night Rogue suggested.

He can't give him the last two Fullbottles and he can't use it because he does not synchronize with it… like… Natsu. Jacen hopes he doesn't regret this, he grabs the two bottles and shouts, "Natsu!" catching the Dragon Slayer attention. "Catch!" Jacen threw the Dragon and Lock bottle to him.

Natsu catches the bottle and looks at it, he remembers what kind of person Lisanna was, sweet and kind but a bit commanding when he does something reckless. He and Happy misses her, she was special to him just like how Lucy became special to him even with their short time together. Jacen tried to save Lucy but failed so now it's his turn.

Night Rogue slaps Jacen to the ground and looks at the Stretch Smash and gestures her to Natsu. Natsu shakes the bottle and opens the cap, as he blocks the Smash attacks and went for a punch the Smash sending him back. he starts to counter-attack, beating up the Smash, "Don't worry Lucy, we'll save you," Natsu says.

"Not bad. But you're only human..." Rogue readies his rifle. But then Jacen rushes in grabbing Rogue.

"Don't!" Jacen shouted.

Rogue pushes Jacen off, as he takes off his driver. "I'm done with you." Rogue hits Sento knocking him onto the ground.

"Jacen!" Natsu exclaims, but as he breaks concentration, he's knocked down to the ground by the Smash.

"Natsu!" Erza shouted with worry but she and the others were too tied up with Gajeel and the Phantom mages to help him.

Natsu groans, he can't believe he's this weak he supposes to be stronger than this but he remembers something Lisanna had said to him, "I like how to use your fist to defend others. We'll be strong together and no matter what I'll always be watching." Natsu clenches his fists he stands up and rushes past the Smash and towards Rogue. Grabbing the Build Driver in the process rolls onto the ground.

Natsu glares at the suited figure and straps Jacen's Driver to his waist surprising the other on his action. He looks at the Dragon Bottle in his hand, "Lisanna, lend me your strength," Everyone hears a screech and looks up to see Cross-Z Dragon flying over them and then folds up its head and tail. As it falls into Natsu's hand, he takes a look at it then shakes the Dragon Bottle again, opening the cap and inserting it into the dragon.

WAKE UP!

He then inserts the dragon onto the Driver.

CROSS-Z DRAGON!

Techno music starts playing as he cranks the lever. The frame forms around Natsu, as the tubes fill with the blue liquid.

"Is he really going to it?" a shocked Elfman said.

"I guess Natsu a Kamen Rider now," Macao looking equally shocked.

ARE YOU READY!

Natsu smacks my hands together and takes a battle pose as he shouts, "HENSHIN!" He reenters the ready stance, as the armor closes around him. As the dragon left half, is the same as the right side closes on him, he also has yellow flames added to the left arm and right leg. With a wing-like attachment was added to his back and added a dragon's flaming head onto the helmet, and the wings creating the shoulder pads.

WAKE UP BURING! GET CROSS-Z DRAGON! YEAHH!

"That meathead actually did it," Jacen smirked.

The Lucy-Smash charges at him, but Natsu blocks her attack and throws a punch that sends the Smash flying backward. He stands up straight, as he grabs the crank and turns the lever. A blue energy dragon, it flies up behind him. As he readies his foot for a kick.

READY GO! DRAGONIC FINISH!

The dragon breathes fire, sending Natsu forwards. He gives a roundhouse kick at the Smash, landing behind her as she explodes into a green flame.

Jacen ran towards the defeated Smash and absorbed the Nebula Gas returning the Smash into Lucy.

"Lucy, are you okay?" Jacen asks her.

"A bit of pain and tired," She mumbled. "I'm sorry."

"You don't need to apologize, Lucy, Night Rogue made you into a Smash to hurt us," Cana reassure her.

"That's not what I'm sorry for…" Lucy muttered before passing out.

The other mages were amazed to see the new power Natsu has gained as a Kamen Rider.

"Amazing, what power," Erza looks at awe.

"Now that's what I call a manly finish!" Elfman smiles seeing his sister bottle save their new friend.

"Kamen Rider Cross-Z… I won't lie but I like the name," Macao crosses his arms.

Night Rogue was stunned by the show of power, "Just one hit."

Natsu summons up his new weapon.

BEAT CROSSER!

"Now he has a sword, seriously?!" Gajeel exclaimed, seeing the enemy Dragon Slayer, become a Rider now has a weapon as well.

"Is it ok to let Natsu have a sword?" Cana joked and looking unsure about the wild Dragon Slayer having a sword.

Taking his new blade, Natsu charges at Night Rogue. As the bat villain opens fire on him but Natsu dodges his attacks and swing at Night Rogue. Cross-Z fast attacks made clear hits on Rogue who was caught off guard. He swings my blade across at Rogue's chest in a blue flame slash. He grabs the grip's end and pull it out and in.

HIPPARE! SMASH HIT!

Natsu charges at Rogue again, as he swings his sword upwards, sending Night Rogue into the air and onto the ground.

"What is this power?!" Night Rogue exclaims.

Natsu pulls the blade again two more times.

HIPPARE! HIPPARE!

He charges at Night Rogue, smashing the blade onto Rogue. Rogue tries to grab the blade, only to feel the head, of the beat.

"Pretty hot, right? It's because it's not just my power!" Natsu says as he pulls the blades trigger.

MILLION HITS!

Natsu pushes down, sending a beat wave that pushes Rogue back.

"Right now…" Natsu exclaims, grabbing his wrist. He reaches down to his bottle holder and grabs the Lock Bottle. He gives it a shake and opens the cap, then inserts it into the blade's bottle slot.

SPECIAL TUNE! HIPPARE! HIPPARE!

Natsu readies himself to swing my blade which was lit with blue fire. "I get the feeling, I can't lose!" He exclaims as he throws the blue flame straight at Rogue.

MILLION SLASH!

The blue fireball flies towards Night Rogue, the villain manages to block, then knocks away the attack. But took some hits from it and falling onto his knee.

"It wasn't supposed to be like this..." Night Rogue mutters before he exudes smoke and disappears.

"Huh?" Natsu looking surprised to vanish.

"Erza!" Jacen calls out getting the Titania attention, "We need to leave and get some of the injured out of here."

Erza looks at some of her fellow comrades and knows they are not all in full strength to defeat the Phantom Lord Guild, "Your right, everyone return to the guild!" She commanded.

Her order made her friends confused and upset, protesting that they can still fight.

"Everyone, we need to rethink our plan, right now we need to get anyone who can barely stand fix up," Jacen told them. "With the Element Four and another Dragon Slayer, we don't know what else they have up their sleeves." The Fairy Tail mages were hesitant but agreed with his words and left back to their home.

"I can take them on Jacen!" Natsu proclaimed.

"We need to get Lucy out of here, Natsu!" Jacen retorted.

The new Rider looks at the unconscious Lucy and clenches his fist, "Fine! Give her to me, you're too injured to carry her." As Natsu carries Lucy on his back as he and Jacen follow their comrades to think of a better plan.

"Don't worry Natsu, you'll show them more of your strength," Jacen promised.

~/~

Elsewhere, a truly unhappy Night Rogue was holding his right arm as he enters a room. In this room was a red figure with a blue mask and crest that looks like a cobra, he is Blood Stalk.

"You knew this would happen didn't you?" Night Rogue questions him.

"I did say, Natsu's Hazard Level has risen up," Blood Stalk shrugged. "I thought it would be obvious Erik."

"My name is Cobra and you work for me, remember that!" Cobra hissed. "You came to me and said you'll follow my lead but lately you have been doing stuff for your agenda."

"I could show you my loyalty if tell me where you hid the box," Blood Stalk suggested.

"Like hell, I will!" Cobra says as he undid his transformation to show a young man.

He has a figure of a slim man of average height with dark tan skin and spiky, upward-styled maroon hair; aside from a tuft covering his forehead and two bangs framing his face and purple slit-pupil eyes. He happens to have snake-like features, with slanted eyes and a rather flat nose. He also sports a simple circular earring on his ears.

He happens to be wearing an elaborate whitish coat with purple inner lining and cuffs intricately decorated by silver-colored motifs, and many studs lined up the chest, the high collar, and the sleeves, which have armbands seemingly made of metal around them above his elbows. Below it, he wears a dark shirt, and he also sports a pair of crimson leather pants held up by a studded belt, with more similar belts circling diagonally the upper parts of his legs, and simple brown shoes.

"Tch, even with Dragneel became a Kamen Rider, I still have the rest of the Fullbottles. But, right now their not my priority, I have to return with my Guild to turn light into darkness," Cobra says.

"Oh, you going to retrieve this ''Nirvana"?" Blood Stalk asks.

"I don't trust Brain but it's an easy way to bring total chaos, for now, don't do anything without me knowing," Cobra glared at him.

"Yeah, yeah, just go be with the snake of yours," Stalk waved him off.

Cobra just kept glaring at him before turning his back on him and left the room. Blood Stalk sat on top of a desk sighing.

"You have truly impressed me Natsu, there is a reason I chose you," Stalk said with an amused voice.