One day in the Tristate area Phineas and Ferb were setting under the tree in their backyard trying to decide what to do. When suddenly they heard a crash!

"Wonder what that could be?" Asked Phineas as he and Ferb went to see what the crash was and found a car had crashed into the fence! But it keep changing back and forth between a car and a robot.

"Wow it's a robot Ferb." Said Phineas.

"Actually I'm an Autobot names Smokescreen." Smokescreen explained. "I'm on my way to a scrapyard near Crown City to help my friends." "But got attacked by some Decepticons I beat them but after driving off realized I'd been damaged I think my T-cog took a hit."

"So now you keep switching back and forth between robot and vehicle mode?" Asked Phineas.

"Yes our T-cogs let us transform since mine's been damaged it's gonna be hard to keep the robots in disguise cover." Smokescreen told them. "I have a friend who's also on his was to the scrapyard we were going there together till we got separated in a ground bridge mishap and agreed to meet there before we lost communication he's a medic so he can fix me when I get there but till then I risk exposing our secret."

"Don't worry we can fix you." Phineas said to him. "Ferb I know what we're gonna do today."

"Thanks guys but do you really think you can fix me." Asked Smokescreen. "I mean aren't you two a little young to be fixing cars or cybertronians for that matter? "

"Yes yes we are." Said Phineas as he and Ferb got to work fixing Smokescreen.
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Meanwhile Phineas and Ferb's older sister Candice and their Mom Linda were on vacation while Phineas and Ferb had stayed home with their Dad.

"This is nice just us girls." Said Candice.

"Yes but no crazy stories about your brothers doing outlandish thing this is just going to be us relaxing." Her Mom told her. "I swear some of the things you come up with."

"That stuff really happened." Said Candice. "But don't worry Phineas and Ferb are back home so nothing's going to mess up this vacation."

The two went to their hotel room but didn't noticed a certain sports car.

Later that night Linda went out to get some ice and suddenly saw a red car with it's lights on high beam!

"Could you please turn those things down!" Linda asked. "Your blinding me."

"Sorry I'll turn them off." Said a voice. "If I blind you then you can't see my beautiful red finish."

"Thank you.." Linda stopped mid sentence when she saw no one was in the car! And ran back to her hotel room! Leaving the red car laughing at her reaction.

"Candice wake up there's a talking car!" She screamed as Candice slowly climbed out of bed.

"What?" Asked Candice.

"That car is alive it's alive!" Linda told her daughter. "It's alive and it spoke to me!"

"Are you trying to make fun of me." Asked Candice. "Because the stuff I tell you about is real." "And cars don't come to life."

"This one did!" Wined Linda.

"OK I'll look." Said Candice who opened the door and stepped out to look. "There no car out here besides Ours"

"What?" Asked Linda as she went out and saw the car was gone. "But it was just here I swear!"

"Sure it was." "Goodnight Mom." Candice told her as she went back to bed.

Then Linda started to go back inside wondering if she had imagined it. When she turn and saw it was back again.

"Hi again." It told her.

"Candice!" "The car!" "the car!" "It's back!" She yelled waking her daughter a second time.

"OK I'll look again." Candice said to her as she walk out of the room again.

"Is it still there?" Linda asked nervously.

"Yes it's a really cool looking red sports car with a pretty shiny paint job." Candice told her. "Thanks for showing me Mom."

"What but it spoke to me." Linda explained.

"It is pretty if your into that kind of thing." Candice told her then went back to bed.

Linda stayed outside trying to figure out what was going on. When she noticed a vending machine had fallen over and went to try to set it back up.

"Man this is heavy!" She thought struggling to put it back to the way it was supposed to be. When suddenly something or someone helped her.

"Need a hand?" Asked the same voice she heard from the car earlier. Then she noticed a giant robot with the same colors as the car.

"Your welcome." Said Knock Out.

Linda screamed and ran back into the hotel room.

"Candice!" "The car is a robot!" She yelled in terror.

"What there are robots now?" Candice asked amused. "Mom let's please just try to get some sleep it's late."

Then Candice and her Mom went to bed but Linda had to sleep with the lights on.
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Back at the house Phineas and Ferb were fixing Smokescreen when Isabella showed up.

"What yah doing?" She asked.

"Fixing an Autobot." Phineas told her. "Wanna help?"

"Sure." She answered and call the Fire Sight girls to help out as well and  Bufert and Belljete also pitched in.

"Hey where's Perry?" Asked Ferb.
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Meanwhile Agent P was called on a mission by Meager Monogram to stop Doctor Doofinsmerts's latest evil skeam.

When he got to Doofinsmerts evil incorporated he came in though the door and was suddenly suck in a cage.

"Perry the Platypus you walked right into my trap so kind of you to use the door by the way." Said Doctor Doofinsmerts.

"Today I am finally going to take over the Tristate area with the help of my new Inator the Jetinator!" Doofinsmerts said pointing at a fighter jet winning a confused look from Agent P.

"What I think your confused my name is Starscream I'm not Waspinator." Said Starscream after transforming from his jet mode.

"Just play along." Doofinsmerts told the seeker. "Now your probably wondering how I was able to build such an awesome inator?" He said to Perry.

"You built!" "I am no one creation special not a humans." Starscream said feeling very much offended. "This guy just happened to see me transform when I was looking for energon and offered to give me an endless supply if I helped him."

"Yes now shut up or I won't give you your energy drinks." Said Doofinsmerts.

"Energy Drinks?" "What?" Asked Starscream.

"I'm going to give you your endless supply of energy drinks with my energy drink inator." Doofinsmerts explained.

"No energon!" "You stupid human!" Starscream yelled at him. "Do you even know what energon is?"

"It's a kind of battery right?" Asked Doofinsmerts.

"No no it's not!" Screamed Starscream. "You can't give me anything goodbye." He said before transforming and flying off.

"No wait come back!" Yelled Doofinsmerts. "Well this is humility." Then let Perry out of the trap not seeing any point. "Cause you Perry the Platypus and you too Starscream." "Not a word Perry the Platypus not a single word." He said before waving goodbye as Perry went home. "At lest nothing blew up this time." Just then his energy drink inator blew up and made a huge mess. "I had to say it didn't I?" Doofinsmerts told himself before cleaning up the mess.
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A few hours later at Phineas and Ferb's house they finished fixing Smokescreen and all said goodbye to him after he thanked all of them for fixing him.

Then Perry got back. "Oh there you are Perry." Said Phineas as the platypus now in his pet mode walked by.

Then Candice and their Mom got home. Then a red sports car suddenly pulled into their drive way.

"Oh no the demon car followed us home!" Yelled their Mom.

Then Jeremy claimed out of the driver's seat. "Hi guys how you like my new ride?" He asked.

"It great Jeremy." Candice told him. "Don't mind my Mom she was having some issues with a red car a lot like that one on our vacation."

"But but but but but!" Said Linda. "I think I'm gonna go on another long vacation after I make snacks for everyone and hope I don't see anymore robot." "Or better I'll just pretend that never happened." She said as she went inside.
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Meanwhile Smokescreen met up with Knock Out on the outskirts of Crown City.

"Hi Knock Out you'll never believe what happened to me I got damaged and these nice humans fixed me." Said Smokescreen.

"Wow I came across this Mom who was very rude to her daughter so I played some pranks on her." Knock Out told him. "It was so funny."

"We can't treat humans like that!" Smokescreen scolded him. "What if you blow our secret?"

"Don't worry I made sure she was the only one who saw me." Knock Out explained. "I promise not to do it again." "I'll have to work more at being an Autobot I guess I still have some Decepticon in me."

"That's OK as long as you don't gaslight anyone else." Said Smokescreen.

Then the two transformers headed to the scrapyard.

The End.

Hope this turned out OK. I decided to put this story on Wattpad and didn't know where to put it since it's a crossover so I decided to post it here. This is one of my older stories from Fanfiction.net. It was my first crossover as well as my first story from the Phineas and Ferb fandom. Hope you all enjoyed it.