Kamen Rider Build - The Deal of Faust

by BioniclesaurKing4t2

Mythical Spellbinder

Kamen Rider Build, the briiiilliant physicist Sento Kiryu, has found himself in a world filled with magical talking ponies with no memory of how he got here. Kinda becoming a recurring trend at this point. Smash are here, too, and what’s worse, a mysterious villain called Faust has stolen all of Sento’s Bottles, taking Build out of commission! Admittedly also a recurring trend now. So, what will happen in Chapter 2? These are chapters, right?

“So let me get this straight,” Twilight said, rubbing her head both from the post-Smash recovery and from trying to follow Sento’s story. “In your world, Faust is an organization?”

Sento nodded. “And they use the same type of equipment as this new Faust, the person.”

The ponies had gathered in the castle’s roundtable room after Sento’s insistence that Twilight would recover fully in a few hours without needing a hospital.

“And you fight them all the time?” Rainbow asked.

“Usually I do better,” Sento replied. “Well, there was that one time the exact same thing happened as here, but that’s not important.”

“Those Full Bottles are, right?” Starlight added before Rainbow could argue.

Sento took out the Unpurified Bottle. “I use them in my Driver to become Kamen Rider Build, but they need to be purified before they have any functionality. They’re useless like this, except to pour on someone and make them into another Smash.”

“So, how do you purify them?” Starlight asked.

“I don’t,” said Sento, “Misora does, it’s her special power. But she’s not here.” He sighed and stared off into the distance. Then something came to mind. “Densha.”

“What?” said Starlight.

“The Densha Bottle,” Sento repeated, “Misora didn’t purify it, Faust just already had it. Well, I didn’t see her do it, maybe that’s one they’d made her do before, but since I don’t know that for sure, that means there’s still a chance there’s another way to purify the Bottle I could cook up.”

“Speaking of cooking,” Pinkie spoke up, “if you need something neat to happen, maybe go talk with Zecora. Trust me, she can make small bottles that can do anything.”

“Oh?” asked Sento. “And where can I find her?”

Zecora pulled a page of chemistry notes off of a flask hanging from the ceiling. She’d almost managed to clear away all of the papers that had infected the place after Sento had gone through and analyzed everything in her ingredients drawers. She’d tried helping him understand how her potion brewing worked as he explained the mechanics of Nebula Gas, but after he’d stubbornly concluded her rhyming to be too much of a distraction, he’d mostly just pulled ahead and figured it all out on his own…leading to even more papers strewn about the place. The fruits of his labor were a large bubbling cauldron of light blue liquid sitting in the middle of the room with that bottle of his dropped inside. And while she alone was cleaning up, Sento had been at her table, recounting to his chaperones Twilight and Starlight about gas boxes and smashing walls or something, she wasn’t invited to the conversation.

“So that’s why I lost my memory of what happened,” said Twilight.

“A giant structure magically springing from the ground because of a small box,” Starlight commented, looking to Twilight. “Sounds familiar.”

“At least it helped bring ponies together instead of splitting them apart,” Twilight replied.

“Well, that’s good to hear,” added Sento.

“You know,” Twilight said, “since you’ve stumbled into this world from another, you could be focusing on getting back home instead of doing all this for us.”

Behind the group, the liquid in the cauldron began to glow.

“That really doesn’t matter,” Sento said. “Not now that there’s a problem here that needs solving. I make sure I see things through. Plus, I’d be equally out of luck if I went back without my arsenal.”

The liquid began flashing repeatedly, faster and faster, as steam started drifting out.

“Well,” Twilight continued, “I have to say that I’m impressed by your commitment. You know, this one time I also—”

Boom! A massive burst of steam erupted from the cauldron as the contents vaporized, everyone but Sento jumping out of their skins and the walls of the hut rattling.

“Oh, it’s done,” he said, leaving Twilight at the table hyperventilating on her calm breathing exercise. Starlight had a hoof to her heart and Zecora was muttering something in Zebric.

Sento stepped up to the cauldron and waved away the steam, curiously peeking in to see that it was now empty of liquid, but that one thing remained sitting at the bottom. Zecora looked over the edge suspiciously as he reached in and carefully picked up the translucent lavender Bottle, a grin conquering his face.

“This is,” he said, looking it over as his spurt of hair sprang up again, “…Unicorn?” The front of the bottle was sculpted like a horse’s head and neck looking forward, with a tall, spiraled horn on its forehead.

“That’s great, right?” Starlight said, coming over. “Now you can use that Bottle to take down Faust!”

The smile immediately left Sento’s face. “The Build Driver needs two Bottles to work.”

“Oh…right,” said Starlight. “And you’re sure you don’t have any others? A spare one isn’t hidden in your shoe or something?”

“I mean,” Sento said, pulling out a clear Bottle, “I have plenty of empty Bottles, but…they’re empty.”

“And without another Smash,” Starlight finished for him, “there’s nothing to fill them with.”

“This is still the worst,” Sento moaned, sinking down to the floor as his hair spurt folded back down.

“Well,” Starlight offered, “what if it…wasn’t?”

Sento looked up at her. “How so?”

“Well, is there a way you could fight with only one Bottle?”

Sento pondered a second. Then he jumped up with excitement. “Of course! If I could make a weapon to Best Match the Unicorn Bottle, I might not need to transform. I need a lab with technology!” He rushed towards the door.

“I suppose there’s probably a room or two in the castle you could use,” Twilight said. “But first—”

“Great!” he exclaimed, racing outside. He slowly looked back in a second later. “Can someone lead the way back to town?”

“I’ll tell you the route so you can come back and forth on your own should you ever need to make another Bottle,” said Twilight, turning to Zecora, “if that’s okay?”

“Him taking over my hut like this on a whim?” Zecora said. “With his papers and explosions, I say, ‘be gone with him’!”

“Well,” Twilight sighed, “I guess this’ll give us a chance to—”

“H-hang on a second,” Starlight spoke up. “I think I could help you with that project.” She gave a nervous smile.

In a shaded alley near the edge of Ponyville, Trixie pulled her cart to a stop. Unlatching, she went around to the back and entered, starting to shuffle some things around.

“Oh, Starlight’s gonna be so surprised,” she said to herself. A second later, one of her smoke pellets triggered, pouring smoke out the door and filling the alley. She stumbled out coughing. “If I survive my own props—cough—jeez.” She looked in through the door and tried moving things around with magic as she waited for the cart to air out. What she didn’t notice was how thick the smoke in the alley had gotten.

In the midst of thickest part of the cloud, a figure had materialized with a panel on their back bearing a round port with slothead bolts around it. The bolts spun a turn, triggering a whirring sound as the surrounding smoke began flowing in towards the figure. As the cloud condensed in, it disappeared into the tips of their pipe wings and under the rim of the pad at the end of their pole horn.

Trixie took notice as the smoke cloud vacated the alley faster than it should have. She’d heard the click and whir, but thought it was just somepony with a vacuum. “Um, thanks? Who’s there? I’m not ready for a show, yet.”

“To think a one-off would need to be part of it,” said a distorted female voice behind her.
Loading

“Huh—ya-haah!” Trixie exclaimed, falling off the cart’s ramp when she turned to look. “Wh-who, what, you?”

“But Sparkler just isn’t fit for this one,” Faust said, holding the Steam Rifle with an empty Bottle attached. She gave the red knob wheel on the side three turns, and it gave the sound of depressurizing steam. “You’ll do fine.”
Devil Steam

Sento placed the completed staff on the map table in front of Twilight. He and Starlight were wearing science goggles and eager grins. His spurt of hair had sprung up again, and Starlight almost looked like the same could happen to her.

“Um, okay,” Twilight asked, looking down at the staff, “what’s with the stick from your old village?”

“It’s my new weapon for the Unicorn Bottle,” Sento said, picking up the tuning fork-tipped staff again. Made of a tan metallo-plastic material and complete with a coil just beneath the tuning end, it was the spitting image of the wooden staff Starlight had once owned, except with a few extra bolts, wires, and a small strip of black caution stripes. There was also an opening with a sliding track for a Bottle at the end of the handle.

“The idea hit me when I suggested he find a way to combine the extraction and purification steps,” Starlight added. “I remembered how I pretended to use the staff to snatch cutie marks, and the design evolved from there.”

“Because Zecora used that potion to purify the Unicorn Bottle,” Sento continued, holding up the Bottle, “I equipped this staff to draw on and replicate that ability through the Bottle’s power. Now a new Full Bottle can be ready right after I defeat a Smash! I can’t wait to test it!” He glanced around for something he could try it out on.

“And I’m glad you two are getting along so well,” Twilight said through a smile thinly veiling something else, “but I just had to find a way to somehow explain to Princess Celestia about this new Faust character’s threat and the whole backstory from another world that may or may not actually be related to her from the memory of only hearing it once while the only one who clearly knew the details was preoccupied on a pet project they’d only just decided to take on and was therefore unnecessarily unavailable for hours on end even when I tried asking kindly to maybe help clarify a thing or two!”

A silent pause fell over the room as Twilight huffed a few times.

Sento scratched his head with a nervous smile, slipping off his goggles.

“We…got a bit sidetracked,” Starlight muttered to Spike, standing beside the table, “didn’t we?”

“Big time,” said Spike.

Sento set the equipment back on the table, but as soon as the Unicorn Bottle touched it, the surface lit up and projected a 3D map, surprising everyone. A small symbol was floating and slowly spinning over a point near the center.

“The Map?” said Twilight.

“The what?” Sento asked.

“It shows ponies where they need to be to solve problems,” she replied.

“Who’s being summoned this time?” asked Starlight.

“I don’t know,” Twilight said, looking closer at the floating symbol. “It’s not one of us. Who has a gear cutie mark?”

At that, Sento quickly leaned over the table for a closer look himself. The symbol was two halves of a black gear rim with a bent line running between them on a diagonal.

“That’s the symbol I use for Build,” he said in surprise. “It has to be talking about me. Solve a problem, you say. It has to mean another Smash, where is that?”

“What do you mean where?” Twilight asked. “That’s right here over Ponyville. Oh, right, you don’t know the land—,” she turned, but Sento and his equipment were already gone, “…scape.”

With a shrug, Starlight raced after him, Twilight and Spike following a second later.

In a burst of glitter and playing cards, a slim-bodied Smash appeared in the middle of the street, several ponies racing into houses or behind corners. It had skinny legs with smooth gray plates, a pale dust blue upper body, and short purple spools mounted on its shoulders wrapped with magenta chains that snaked down its arms and trailed from its wrists. Its head was a purple top hat with a small pale purple crystal at the center and a short stiff cape trailing from the back. The Trick Smash turned to the new arrivals as Sento and the others ran into view.

“Quit poofin’ around!” came Applejack’s voice from the other direction.

The Trick Smash spun and tossed a handful of playing cards at her as she charged it, the crystal on its face flashing like a camera strobe. With each flash, one of the cards grew giant and a corner jabbed into the ground, forming a wall in front of her.

“Alright,” Sento said, holding up the staff and Unicorn Bottle as he stepped forward, “time to test this new Tuning Staff out—”

The Smash threw its left arm at him and the chain shot out, the spool spinning as it emptied, the chain flying over and slamming into him, quickly snaking around him as he fell to the ground, the staff and Bottle clattering down next to him.

“Sen—”

“Sento!” Starlight said, racing up to him. Twilight was a bit glad she’d been drowned out.

Sento looked down at the loops of magenta chain cocooning his arms and torso. “Well, this sucks,” he stated plainly. A new chain slowly filled up the Smash’s empty spool as a replacement.

“Don’t stress yourself, new guy,” Rainbow Dash said, floating over, “we’ve got it this time. Right, AJ?”

Applejack spun and tossed a lasso at Trick, but it reached out and caught the loop of rope with a poof of smoke and glitter, the cloud fading to reveal it holding a now-lassoed Spike.

“How the—what?” Spike stuttered. Applejack dropped the rope in surprise, and Trick tossed Spike aside.

“Spi—”

“Spike!” Starlight said, racing over and catching him with magic.

Twilight snorted. Okay, this was getting old.

Applejack charged at the Smash again. Trick simply watched as Applejack reached it, jamming her front hooves into the ground and spinning around, kicking out at it, but it vanished again in a burst of glitter and cards like it had several times before Sento’s arrival.

“You’ll never hit him if you keep doing that,” Rainbow said, flying over to Applejack.

“And what do you suggest?” she snapped. Trick reappeared a house down the road in another glittering flourish of smoke.

“Doing it faster!” Rainbow shouted as she shot at the Smash. She twisted to land a kick, but on impact, its shape collapsed into a tower of cards. Before she could react, a cape spun from thin air behind her, Trick swirling out of it and swinging the chain on its right arm, smacking her out of the air.

Trick continued the swing, the chain whipping wide around the general area, snapping at the ground below Applejack as she leapt aside, and bouncing off the shield Twilight had put around her and Sento. The impact rippled the shield down to her horn, making her grab her head as the shield faded.

“There’s just no hittin’ this thing,” Applejack said, frustrated.

“There is if we match magic with magic,” Twilight said.

“You really don’t look up to it yet,” Sento said from the ground.

“And you’re any better?” she replied. She lit up her horn and teleported out in front of the Smash, but swayed a step upon arriving.

Trick casually flicked her forehead, sending her skidding back about twenty feet. She angrily shook her head and fired a magic beam at it, but it tossed out three cards, its face crystal flashing to expand them into triangular barrier. The beam hit and blasted it into a spray of 52 pick-up, but a magenta chain swung through the clutter and smacked Twilight flipping several times to the ground.

Trick stepped forward and bowed. It drew back its right arm and threw the chain beelining at Twilight, links rattling as its length speedily unspooled, but Starlight jumped in front of Twilight, horn glowing. The chain lurched to a stop in midair, inches from Starlight.

“Huh?” Starlight said, her horn fading. She hadn’t done that. Her gaze followed up the chain to discover that Trick had itself grabbed it at the source with its right hand. After hanging straight for a second, the chain dropped limp to the ground. Trick was standing stock-still. Starlight didn’t know what this was about, but her instinct sent a blast of magic that sent Trick to the ground, the spool slowly retracting the chain back.

The Smash pushed itself to its feet again, raising its arm to swing but forcing itself to freeze up again upon seeing Starlight. Getting steadily more freaked out, Starlight blasted it again.

Applejack pulled Twilight back over to the sidelines by Sento, who was still on his back and struggling inside the chains. A click was quickly followed by a sliding and latching sound.

“Need any help?” Applejack asked, stepping over and looking for either end of the chain.

“Nope,” Sento said. The Drill Crusher suddenly stuck out from beneath chains next to his face, Applejack jumping back a step. “I got this.”

Looking away, Sento triggered the Crusher, the drill blade grinding against the chains and spraying sparks. A few seconds later, the first loop snapped, quickly followed by the next, and the next, until the chain cocoon split open like a zipper as Sento sat up, now adorned with his Driver.

“If you still had that,” moaned Twilight, “then why’d you need to make a new weapon?”

Sento paused.

Trick stumbled back from another blast, its torso smoking. It raised its right arm, but grabbed it with its left hand and pulled it down to its side again. It grabbed the chain and wrapped it around its right wrist several times, pulling back as its arm tried reaching at Starlight.

“What’s wrong with this thing?” Starlight asked in a panic, another blast charging itself. “How come it’s not fighting me?”

“It probably has something to do with who that is,” Sento replied, walking up beside her with his equipment, “so let’s get a look inside.” He put a hand on the back of her neck. “I got it from here.” Starlight took a deep breath and stepped back.

Sento shook the Unicorn Bottle several times and twisted the cap, sliding it into the open slot at the end of the Tuning Staff’s handle, a purple image of its emblem briefly appearing over it.
Ready, Go!

The tuning fork end of the staff started spinning to the right and made his Driver’s cyclic clanging noise (because it just sounded so good). On the lower half of the staff were a pair of button triggers, and as he aimed it at the Smash in both hands, he pressed the first trigger. A glow appeared between the spinning tuning prongs, shooting a beam of bluish energy that hit and connected to the Smash. He pressed the trigger again.
Vortech Break!

A bulge of energy shot up the beam, hitting the Smash with green flame explosion and knocking it to its back, the beam staying connected. He pressed the second trigger.

The clanging sound faded as the tuning prongs slowed to a stop, then resumed as they began spinning to the left. The Smash form began disintegrating, the extracted essence getting pulled back along the beam and collecting between the prongs. As the last of the essence was extracted, the beam’s connection broke, and a symbol flashed over the essence; the bulge of materials was slowly drained into the spinning prongs as a dull blue glow began flowing down the coil. Starlight’s attention, however, was elsewhere.

“Trixie!” she shouted, running to the pony lying where the Smash had been, now stirring.

“Nnnhg, Starlight?” Trixie said weakly, leaning up. “Surprise,” she said, raising a hoof before flattening again. “What happened after I got to Ponyville?”

As the glow from the coil drained out of it, there was a flashing from the center of the staff and a cloud of steam burst out. The prongs slowed to a stop again, and when the steam died down, Sento bent the staff in half like a shotgun to open up the second Bottle track hidden inside. He grabbed the Bottle inside, but let go and shook his hand. He grabbed it again a few seconds later, pulling out the newly purified dust blue Bottle and twisting the cap closed. On its front was sculpted star-tipped wand trailing a curving streak. “Works like a charm,” he said.

Then he heard more steam flowing. He turned to see that the small cloud produced had drifted away and expanded, and was now being funneled into the pipes on Faust’s suit. She was holding the Steam Rifle.

“Starlight…,” Trixie muttered nervously, edging herself a bit away.

“What happened after you arrived?” Starlight repeated. “She did.”

“You again?” Faust said to Sento. “I deal with you for interfering with Twilight, and now you manage to crawl back into my way.”

“Him?” Starlight interrupted. “Excuse me, but you’re the one who messed with Twilight, remember?”

“You dare speak to me?” snapped Faust. “You’re as much an intruder as he is.”

“Huh?” Starlight said. “Wait, how?”

Faust turned back to Sento. “Give me those Bottles. You don’t know what they’re for.”

Sento sighed. “You may not be part of the Faust I know,” he said, retrieving the Unicorn Bottle before dropping the Tuning Staff, “but whatever you’re after, I’ve decided I’m stopping you. Now,” he held up a Bottle in each hand, “shall we begin the experiment?”

He began shaking the Bottles, spawning an array of floating equations drifting out from behind him. Glancing at them, however, he saw that a number of the normal letter variables had been replaced by cartoon stars, horseshoes, and smileys. One equation floated by that read “sun + lollipop + rainbow = 2”. Sento chuckled. Oh, this place. He stopped shaking and twisted the caps, putting the Bottles into his Driver.
Unicorn
Magic
Best Match!

“Best Match!?” he said in surprise, looking at the pair. “Are you serious? What luck!” He grabbed the handle with a grin and began turning the crank, tubes tracing out from the Bottles and into the base that appeared around him, filling with violet and pale blue liquid while forming the frameworks and inner tubes.
Are You Ready?

He pumped out his left arm as the inner tubes solidified into armor. “Henshin!” He crossed his arms and threw them down, then the frameworks slid in and he was encased by the armor, the tubes retracting away as steam poured out.
Mythical Spellbinder! MagiCorn! Yeyyy.

His left leg, right arm and chest, and left face were lavender, and his right leg, left arm and chest, and right face were a bright dust blue. His right foot had a printed chain decoration wrapping around it, and the top of his left foot had a printed spiral horn pointing to his toes. A short pole was sculpted onto his left forearm armor and led to a thick yellow five-pointed star crystal over his wrist, and a lavender spiral cone outline was attached onto his right wrist, spreading out as it extended up to the level of his elbow. His right eye was a dust blue star with a wand handle and sinusoid magic trail sticking out, and his left eye was a lavender profile view of the right side of a (real-world) unicorn’s head, the snout aiming down and a long horn spiking up.

Starlight and Twilight looked on, giving a collective, “Wow.”

“I’ve found the winning formula,” Sento said, tracing his finger up the wand eye cover and flicking.

Faust shifted the Steam Rifle and held up a white Bottle, snagging Sento’s attention in a second. Giving it a shake, she twisted the cap and plugged it into the Rifle, the white image of a panda face briefly appearing.
Full Bottle

“Hey,” Sento said, “those are my—”

Faust flipped the Rifle in her hand to grab the back and hold it like a sword, clicking the trigger.
Steam Attack

A cloud of steam poured from Faust’s horn and wing pipes, engulfing her and shooting over to Sento. She burst from it and swung down the blade of the Rifle with a five-wide spread of white claw streaks, raking across his chest with sprays of sparks and sending him to the ground.

“So much for your winning formula,” she said. She swung the weapon down again, but Sento held up his blue Magic arm, the star on it glowing. A magic dome rose up around him, the Rifle blade hitting it and stopping, the claw streaks fading out. Sento jumped to his feet, raising his left arm high, the dome expanding and pushing Faust back before fading.

“Magic wand, huh?” Sento said, looking at the glowing star. He swung out the Drill Crusher, moving the Unicorn Bottle into its slot.
Ready, Go!

The drill blade began spinning as a lavender unicorn horn energy projection appeared around it.
Vortech Break!

Sento thrust the Crusher towards Faust, the spinning projection flying off; she held up her left arm to block it, but it grazed past her arm and hit her chest plate, pushing her back while spraying sparks, feet skidding through the dirt. She raised the Steam Rifle and slashed it down, the claw streaks cleaving the projection into chunks that shattered away. She came to a stop, quickly stamping down for stability. She glared up at Sento, panting.

“This isn’t over,” she said. “My world will come.” Smoke poured from her pipe wings and horn and covered her, wrapping in on itself before sparkling and fading away, leaving nothing.

Sento pulled the Unicorn Bottle out of the Crusher and removed Magic from the Driver; his armor glowed before splitting off of him. He took another look at his two new Bottles as the ponies approached.

“So, this is what you’re up to now, is it?” Trixie commented.

“Looks that way,” Starlight replied. She walked up to Sento. “Guessing you’re not done yet then, huh?”

“Not by a long shot,” he said.

“Is it bad for me to say that I’m glad you’re sticking around a bit longer?” she asked.

“I have that effect on people,” Sento said. “Well, ponies in…you know what I mean.”

Comments

[Mystic Sunrise]

About bucking time someone did a Kamen Rider Build crossover. Considering the role Faust has in that series, compared to MLP...

I'm going to need more popcorn.

[Kailord]

Like it especially with the Kamen Rider being build, and I cant wait for more.

[Ze1a7in]

...Is the title of this fic based on the term "Faustian Bargain"?

[BioniclesaurKing4t2]

8798165
Yep. (It was the only fitting way I could think to put "Faust" in the title, considering her importance to the story.)

[Ze1a7in]

8798526
I approve of the wordplay.

[cyberlord4444]

8798526
Not bad, I have a few ideas for best matches if you're interested.

[BioniclesaurKing4t2]

8798907
The whole story is planned, it's just turning notes into paragraphs that takes time. And dealing with a half dozen other stories at the same time. My ideas may all be mapped out and mean something to the plot, but I always like hearing other ideas, though.

[cyberlord4444]

8799118
Apple, Hammer
Impact Harvester
Apple Hammer

Cupcake, Cannon
High Calorie Artillery
Cupcakannon

Eye, Chain
Binding Gaze
Eye Chain

Pegasus, Storm
Lightning Wing
Pegastorm

Butler, Propane
Fire Star Service
Probutler

Princess, Sun
Master of the Dawn
Princessun

Baku, Moon
Dream Feaster
Bakumoon

Draconequus, Dice
Roll for Reality
Draconedice

(Couldn't think of one for Rarity, so have 1 for Derpy, and one that's not MLP related, but might still be fun)

Muffin, Bubble

Scientist, Shotgun
Analyze and Assault
Scinshotgun

[Ri2]

That's an AWESOME Best Match.

And oh dear, I think I see what Faust is doing. She's angry her original vision for the world's been utterly changed and is trying to reset it back to how it was in season 1. Maybe even further.