The Coolest Coaster EVER! - Phineas and Ferb/Once-ler Crossover (Part 1 of 3)

Plot: This is basically based off the very first episode of Phineas and Ferb, (Rollercoaster), but with Smog and Onciebot as the latter. I don’t know why anyone hasn’t done this before.

There’s a hundred and four days

Of summer vacation, til school comes along just to end it

So the annul problem for our generation

Is finding a good way to speeeend it



Building a rocket

Or fighting a mummy

Or climbing up the Eiffel Tower

Discovering something that doesn’t exist

(Smog: Hey!)

Or giving a monkey a shower


Surfing a tidal wave

Creating Nanobots

Or locating Frankenstein’s brain

(Smog: It’s over here!)

Finding a Dodo bird

Painting a continent

Or driving our brother insane!

(Greedbot: SMOG!)

So as you can see there’s a whole lot of stuff to do

Before school starts next fall

(Come on, Cogs!)

So stick with us cause Smog and Onciebot are gonna do it all!

So stick with us cause Smog and Onciebot are gonna do it all!

(Greedbot: STEEEEAAM!!! Smog and Onciebot are making a title sequence!)


It was a bright, and sunny summer day in Thneedville. A perfect day to just sit and relax, and do nothing. And Smog was having none of it. He couldn’t stand not doing. He hated sitting under the same old Truffula tree in his backyard with Onciebot, doing nothing. He let out a frustrated sigh.

"GAH!! I can’t take it! This is asinine! It’s only been a week into the summer, and I haven’t done anything! I’m gonna pull my goddamn hair out!!" Smog shouted tugging at his hair. His adopted "brother", Onciebot, looked up from his book then at his little brother. "Well instead of complaining about it, why not do something?"

"Like what?" Smog asked, leaning against the tree, arms crossed. He blew hair from from his face. "Tsk, this day is more boring than that rollercoaster at the town fair! I mean, what kind of rollercoaster lasts only 1 minute!? LAME!"

Onciebot giggled at his little brother’s fit, then picked up Cogs, a nubcat that Crud had given Steam as a gift. He pet the cross-eyed animal’s fur, enjoying the purring noise it made. “Why don’t we just build one?”

A light went off in Smog’s head. That’s it. They’d build a rollercoaster! One that was faster, and with corkscrews, and rubber snakes! Yes, that’s what they’ll do! “Oncie, you’re a genius! Thanks to you, I know what we’re gonna do today!” he said, hugging his brother with a grin

"Hey boys." Steam said walking in the backyard, wallet in his hands. "What are you guys doing?"

"We’re gonna build a rollercoaster." Smog said pulling a notebook out of his shorts pocket. He flipped it open and being making a list of all the supplies they would need.

"How cute~ Well, your father and I are about to head over to the grocery store, we’ll be back in an hour." Steam saiding stuff the wallet back in his pocket 

"Ok, daddy. Oh, can you pick up some more peanut butter? We’re all out." Smog said setting up his work station. 

Steam ruffled his son’s hair,”Of course I will. Be good, and clean up any mess you make.” He kissed the boys’ foreheads then walked out the backyard gate leading towards the driveway. Greedlerbot peeked out the kitchen window, watching the couple get into the car. He dashed outside then stood outside the passenger side of the car.

'You told them I was in charge right?' Greedlerbot wrote out on his chalkboard in red chalk

"Ah..noooo." Steam said "Was I suppose to?"

'Um, yeah. What if an emergency happens?'

"Like what?"

'Liiiike…oh! What if a satellite falls from space and crash landed in the living room? :3'

Steam stared at Greedlerbot for a minutes before he said drily,”If that happens then you’re in charge.”

Greed gave a big grin as he waved goodbye to Steam, then barged into the backyard. 

"Steam…said…I’m…in…charge……… conditionally." Greedbot said through his recordings. Smog looked up from his blueprints then shrugged,"Whatever." he said, uninterested


"Building a rollercoaster." Onciebot said with a smile. Greed narrowed his eyes at the two. "I’m….watching…you..don’t forget…I’ …. conditionally."

With that Greed walked into the house, peeking out the kitchen window.

"Yeah, yeah.." Smog said waving his older brother off. "Hey, did you call the metal works guy yet, Once?"

Inside the house, Greed was still watching Onciebot and Smog until he heard the computer go off. Rushing over he saw that it was a message from Norma. He smiled then typed out a hello.


Norma: Hi Greedy~! What’s up?

Greedlerbot:Nothing much, just watching my brothers. They can be annoying sometimes.


Norma: Aw, you should be happy to have brothers like them.

Outside the boys, and Cogs the cat where outside hauling stuff in the backyard via a little red wagon. Greed didn’t seem to take notice, until he heard a noise. He frowned then shut the window.

Greedlerbot:I guess. I mean, they are geniuses and everything..but watching them can be tedious. 


Norma: Well are you watching them right now?

Greedlerbot:No, why?


Norma:They’re building something. I don’t know what it is, but it’s big. I can see it from my house.


In flash Greed leaped from his chair, and ran out the backdoor. What he saw outside was the beginning stages of a rollercoaster. He made a grinding noise, as if asking a question in an angry tone. Smog looked up from his toolbox then waved at Greedbot.

"Oh, hey! Sorry about the mess, the delivery guy wasn’t sure where to put the bars." Smog said wiping oil off his face 

Greed made another grinding noise then stomped his foot angrily. “I’m…telling..Steam! And..when……you’re…going..down!” he said, baring sharp bronze teeth. He clicked his heels together, activating the rockets under his shoes. “DOWN! D…O..W..N!” he said before flying off.

Outside on the driveway, a pretty redheaded girl wearing a simple purple shirt and blue jean shorts, looked up at the sky seeing Greedlerbot fly off in a huff. She shrugged, then walked inside the backyard. She sighed a little when she saw Smog. He was so cute. “Hey, Smog, what’cha doin?” she asked in a sweet tone. She had a slight Scottish accent. 

"Oh, hey, Kim." Smog said, not looking up from his toolbox. Kim smiled then looked over at Onciebot. "Hey, Oncie." The young bot waved his hammer at her in response then began hammering in a nail. It bounced back and hit him in the face. "Ow…"

"Your brother is accident prone, dude." Kim said looking over at Smog again "So, what’cha doin?"

"We’re building a rollercoaster, duh." Smog said, a little annoyed

"Wow, that’s cool." Kim said, putting her hands behind her back "Hey, um, I’m going to the pool and I was wondering if you wanted to go swimming with me~?"

Smog gestured to the unfished rollercoaster,”Uh, kinda busy here.”

"Oh…right. Well, maybe later then. I’ll come back over when you guys finish your rollercoaster. See ya!" Kim waved bye then left. Smog finally came out of the toolbox, a box of rivets in his hands.

"Yo, OB, you got enough rivets there?" he asked holding up the box

Oncie nobbed, a rivet gun in his hands. He aimed it at the track then began to fire. He blew on it after he was done, then looked around. “Where’s Cogs?” he asked