A/N: There is slight Candace/Jeremy and Isabella/Phineas but no more so than in canon. All other relationships are purely platonic.

This is my first fic in this fandom so reviews are appreciated

Roger Doofenshmirtz was throwing a party.

This was nothing new in and of itself - the mayor threw parties every other week, entertaining important officials and whatever dignitaries were visiting at the time. What was new, however, was that all of Danville was invited.

Heinz Doofenshmirtz knew this because it said so in fancy print on his invitation. Evidently his brother hadn't spared any expense. The border was lined with gold leaf and the envelope was stamped with the official Danville mayoral seal, only brought out on special occasions.

Briefly he wondered if Perry and OWCA's other Danville agents had been invited as well.

He turned his attention to his most recent Inator. Soon, he'd have a chance to use it.

Heinz set the invitation down on a table, electing to ignore the frustration it brought forth and putting the finishing touches on his invention.

Perry landed in his lair, sitting down and noting the envelope on his desk. It looked similar to the ones the Flynn-Fletcher family had received that morning, though the wax seal was one of OWCA's designs rather than the mayor's.

Inside, the letter read:

Agent P,

As I'm sure you know by now, the mayor is hosting a party tomorrow night. He's invited all of Danville, including Dr. Doofenshmirtz. Your job is to attend and keep an eye on him.

Major Monogram out.

Perry sighed, leaving the letter on his desk and taking the elevator back up to the yard. Finally, a day off.

The Inator was finally complete. Every detail was there, down to the big, red, self destruct button.

Heinz glanced at a clock, noticing the time.

"And three, two, one," he muttered, looking at the door as Perry the Platypus kicked it down.

He clapped his hands together, grinning.

"Perry the Platypus, right on time." Perry glanced up at the ceiling, raising a brow. "No, no trap today. There's no time. Come on, let me show you my newest scheme. Nice suit, by the way."

His nemesis followed him into the next room, gazing at the contraption before him. It was smaller than most of Heinz's inventions - the size and shape of a large water gun.

"It's not evil per say, just a bit of a harmless prank. To be honest, I'd rather not blow up tonight. Anyway, behold the Stage-Fright-Inator!" he proclaimed. "Anyone who is hit by its beam will be overcome by stage fright and will lose the nerve to speak. When Roger makes his welcome speech, I will shoot him with the laser, and he will be embarrassed in front of the whole Tri-State Area!"

Perry turned around, heading toward the door.

"Wait, why don't you come with me? Like I said, it's not really evil, so you get to keep your conscience clean."

The platypus rolled his eyes.

"Please?" Heinz pleaded. "Come on, I can't go alone and...well, I don't really have any other friends. Even Norm's going with a few robots."

Perry tilted his head to the side for a moment and chittered. Technically, he'd still be doing his job. He gave a thumbs up and wondered for a moment what he'd be getting himself into.

This is not just a party, Candace thought as she walked into the ballroom. The only word she could think of to describe it was "elegant".

"So, what's the game plan?" Stacy asked. "Are you gonna try to lose a shoe again?"

"Not after last time," Candace shuddered. "Oh, look! There he is!"

Jeremy, having spotted the two, waved and walked over.

"Hey, Candace. You look great. You too, Stacy." he greeted.

The redhead giggled.

"Hi, Jeremy," Stacy said, elbowing Candace.

"Hi," she said dreamily.

"I'm gonna go find some of my friends, but I'll be back. Save me a dance," he said.

Candace sighed.

"Did you hear that, Stacy? He asked me to save him a dance."

"That makes sense, considering the fact that he's your boyfriend," Stacy rolled her eyes. "Anyway, are you sure you need some kind of elaborate scheme? He already likes you."

"Oh...alright, I guess. Come on, Phineas and Ferb are probably doing something bustable."

Isabella groaned, wishing for a moment that Phineas wasn't so oblivious. She fidgeted with the sleeve of her purple and pink dress, breathing deeply. She just had to be obvious...more so than she was already.

"Hey, Phineas?" she began. "I was wondering if you wanted to-"

She turned around and frowned as a loud crash came from the balcony overlooking the room.

"What was it you wanted, Isabella?" Phineas asked.

"Well, I wanted to know if you'd like to dance," she said.

His grin brightened.

"Sure! Come on, let's go find everyone else." He grabbed her hand and led her across the room, ignorant to her sighs.

"Alright, Perry the Platypus. This should be the perfect spot to fire the Stage-Fright-Inator from," Heinz said, leaning on the railing to observe the party below.

"Hey, look! There's Norm. Huh, I guess he actually did find some robot friends. Good for him. I'll be honest, I was expecting him to show up with a vending machine."

Perry sat on the railing, observing his host family and their friends. He spotted Pinky, who appeared to be avoiding Isabella, as well as Major Monogram and Carl. In fact, most of Danville's OWCA agents and their nemeses were there.

"Is that Love Händel?" Heinz asked.

Perry chittered, pointing across the room where a stage had been set up.

"Ugh, of course they'd perform at Roger's party. Well, we have some time before my brother makes his speech. Is there anyone in the Tri-State Area you've been wanting to get revenge on?"

He just glared.

"Oh, come on. It won't really hurt anyone." the doctor frowned. "Like I said, it's not evil."

Perry just crossed his arms.

"Fine, fine. I get to pick first, then." He scanned the room, aiming the Inator at Major Monogram. "How about Francis, hm?"

Heinz glanced at Perry, who gestured as if to say "go ahead". Nothing about keeping his boss from being embarrassed was ever part of the job description.

He fired the laser and suddenly, the Major froze.

"Carl, I just wanted to tell you that-," he stopped talking suddenly, clenching a glass of punch.

"Um, sir? What did you want to tell me?" Carl asked.

"Nevermind."

"Hah! See, Perry the Platypus?" Heinz frowned, turning to the window behind them. "Hey, what's that noise?"

A large vending machine soared through the window with a crash. It picked itself up, hopping over the balcony and joining Norm.

They were silent for a moment.

"Huh."

Isabella sighed.

"Phineas, I meant just us," she said.

Phineas stopped.

"Sorry, Isabella. Can't hear you over all this noise. What did you say?"

She tensed up. How could she be brave and tell Phineas how she felt when all these people were around, just waiting to laugh at her? She would just ruin their friendship. She couldn't do that.

"Nothing."

"Well, if you don't appreciate the Stage-Fright-Inator, maybe you'll like the Water-Balloon-Inator more," Heinz declared, pulling out another water gun-shaped invention.

Perry shrugged, taking it from him and looking at the controls. There weren't any buttons or dials visible - only a self destruct button and trigger.

He aimed it at Major Monogram and watched as he was hit in the head with a water balloon.

"What the-" Monogram frowned, turning around to look for the culprit. He spotted Perry sitting next to Heinz and turned to the intern.

"Carl, I think we have a situation."

Carl followed his gaze and gasped.

"Agent P turned to the dark side," he said incredulously.

Monogram shushed him.

"Don't make a scene, Carl."

"Oh, wait. He just texted me, look," Carl held up his watch. It read, "it's good".

Perry chittered, aiming the Water-Balloon-Inator at his next victim. Love Händel would soon be soaked.

Quickly, nearly everyone in the crowd below had been hit by one of the Inators. At some point, umbrellas had been distributed for those who cared enough to not get wet, as well as Roger Doofenshmirtz and the various dignitaries and officials attending.

"People of Danville and the Tri-State Area, welcome. Thank you for taking the time out of your busy schedules to-" the mayor cut himself off suddenly, beginning to shake. He fidgeted with his jacket cuffs, shifting his weight from side to side.

Danville's citizens frowned, and murmurs began spreading about his sudden stage fright.

Heinz grinned.

"Finally, Perry the Platypus. After all this time, I have succeeded!"

Perry smiled, shooting a water balloon at the speechless mayor.

After a moment, the doctor pulled the trigger again and Roger continued where he left off.

He shrugged in response to Perry's questioning look, simply continuing to fire his Inator at random people in the crowd.

Perry followed suit, selecting a new target and shooting them with deadly accuracy.

Isabella felt a sudden rush of courage and took a deep breath in, closing her eyes for a moment. There was nothing to be afraid of. She could do this. She would do this.

Phineas stood in front of her, scanning the room for their friends. She tapped him on the shoulder and he spun around.

"Phineas, what I meant was just the two of us."

She held her breath, balling her fists up. It was too late to take her words back now.

"Oh, okay," Phineas smiled. He took her hand and led her across the dance floor, ignorant of her relieved exhale.

One by one, everyone was picked off. Even Phineas and Ferb were not spared Perry's wrath as he left none standing. Finally, there was only one.

Heinz's expression turned fearful as he dropped the Stage-Fright-Inator and backed away.

"Wait, Perry, you don't have to do this," he pleaded.

Perry the Platypus just shook his head, growling. Soon, he had his nemesis cornered. He adjusted his fedora and aimed his weapon.

"Perry, please." His voice shook.

He pulled the trigger.

None would leave this night untouched by the Water-Balloon-Inator.

"Oh, look what you've done. I'll have you know this was a new suit, Perry the Platypus," Heinz frowned.

Perry shrugged, smiling. He chittered and handed him the Inator.

A moment later, Heinz had exacted his revenge.

"There. Now, we're even," he said, giving it back to him.

Perry took his place on the railing and resumed firing.

"Listen, Carl, I just wanted to let you know that I appreciate everything you do for OWCA," Monogram said.

Carl beamed and was promptly hit in the face with a water balloon.

Candace shrieked and lunged blindly in what she hoped was Buford's direction. Punch dripped from the overturned bowl on her head, staining her face cherry red.

Phineas and Ferb built the catapult, but the bully had aimed it in her direction.

She lifted the bowl up, scanned her immediate area, and flung it at Buford. He dodged with a yelp and hid behind Baljeet.

He ran, equally afraid of her as Candace advanced toward Buford. He backed away into Stacy, who dropped a cup of ice on top of his head. He jumped and vanished into the crowd.

Candace accepted a towel from Stacy, drying herself off as best she could. She frowned in disgust.

"Ugh, look at me. I'll be sticky for ages," she groaned.

"At least Jeremy wasn't watching," Stacy offered.

"Yeah, that would have been embarrassing. Come on, let's go find him," she sighed.

"So...what's the point of this?" Isabella asked, looking up at the catapult.

"Well, you know how someone's firing water balloons from the balcony? I figured we could send a few their way," he explained, revealing a box of unfilled water balloons with a flourish.

Ferb nodded, pointing up to where a strangely small figure was sitting.

A balloon smacked him in the face and his expression darkened.

"It is on."

A flip wipe later, they had prepared their ammunition. Each water balloon was guaranteed to give a good splashing at over a yard in diameter.

"You know," Phineas said, squinting at their opponent, "they look kind of familiar. I can't quite put my finger on it, though."

He turned back to the group.

"Anyway, let's arm this thing."

Isabella and Ferb loaded the water balloon while Baljeet and Phineas aimed it. Buford remained hidden behind the contraption, warily watching for Candace.

"Looks good, everyone. Ferb, you want to do the honors?"

His brother nodded, releasing the mechanism. They watched as the giant balloon flew toward their foe and burst, covering them and the pharmacist standing next to them in water.

After a few minutes, a war had developed.

Perry fired the Water-Balloon-Inator with deadly accuracy while his nemesis worked on providing cover.

"There," Heinz said proudly. "The Pool-Noodle-Inator is finished."

It looked like a cannon, albeit a rather futuristic one. Heinz pressed a button on the back and a pool noodle shot out. It hit Buford, who pulled out a foam sword and waved it threateningly.

Perry felt odd carrying a foam sword and shield, but he couldn't very well actually fight his owners. He donned a holster and placed a water gun inside. It had been modified to automatically draw vapor from the air so that he wouldn't have to manually refill it.

Heinz was outfitted similarly, though with the Water-Balloon-Inator instead.

Perry knew that he was probably taking a risk by being in such close proximity with Phineas and Ferb, but if they hadn't already recognized him, they likely wouldn't.

They walked down the stairs to the first floor of the ballroom, swords and shields in hand.

Perry charged at Baljeet, dodging his swipe and leaping over him. He landed a hit and moved on to Buford.

He glanced at Heinz, who was battling Phineas from behind a table. He seemed unaware of Isabella sneaking up behind him, water gun in hand.

Perry somersaulted beneath a tablecloth and swiftly shot at Isabella. Heinz turned around and he gave a thumbs up, joining him in firing at Phineas. He saw Baljeet, Buford, and Isabella suiting up in foam armor out of the corner of his eye.

Suddenly, Phineas vanished.

Perry frowned, scanning the room. Where were Phineas and-

A hundred gallons of freezing cold water dropped on them from above.

He felt Isabella grab him from behind, pressing a foam sword to his neck.

An elevator descended from the ceiling and Ferb stepped out, Phineas a step behind.

Perry looked over, noting that Heinz had managed to avoid capture. He was holding his sword in one hand, the Water-Balloon-Inator in the other.

"What do you want done with them, Ferb?" Isabella asked.

"We have a proposition for you," he said softly, addressing the scientist. "Admit defeat and we won't hurt your friend here."

Perry shook his head frantically. As much as he loved his family, they couldn't lose.

Heinz looked at him helplessly. The stillness seemed to last forever.

A moment later, he dropped his weapons and placed his hands on his head. Buford tied his hands together with a tablecloth as Perry managed to break Isabella's grip, jumping on top of a table and pulling a remote out of his pocket. He pressed a button and the Pool-Noodle-Inator began firing.

Amidst the sudden chaos, he grabbed the weaponry that had been taken from them. Perry untied the tablecloth.

"Thanks, Perry the Platypus," Heinz said. "Come on, we need to rethink our battle strategy."

"Are your brothers fighting a pharmacist and...a platypus?" Stacy asked, pointing across the room to where her brothers were, indeed, doing just that.

"Yes," Candace replied morosely.

Stacy raised a brow.

"You're not gonna try and bust them?"

She sighed. Her parents weren't even in the building - they'd left soon after water balloons had started falling, promising to pick them up once the party was over.

"No. No, I'm not."

Perry dove behind a chair as Baljeet fired in his direction. He whistled and a sprinkler on the ceiling activated, smirking as Baljeet and Buford were drenched. Norm picked them up and placed them in the pen Janice (a vending machine) had made.

He looked up to see Isabella ziplining in his direction. She dropped onto the table in front of him and lunged.

Perry pulled his sword from its sheath and blocked her, overturning the chair and jumping onto the table behind him.

He stayed on the defensive, dodging blow after blow. Isabella feinted and slammed her shield into his side. It didn't hurt, but he wouldn't be able to keep this up for much longer.

Heinz snuck around behind her and tossed a water balloon, giving Perry a chance to knock her sword from her hand.

She sighed as Norm deposited her in the pen next to Baljeet and Buford.

Perry's eyes widened as he saw a large robot, about Norm's size, advance on them. He could see Phineas and Ferb piloting it within the head.

It shot at them with a water gun. Perry pushed Heinz out of the way and raised his shield.

"Oh, wow. How did I not notice that?"

Perry just shrugged.

"Well...I'll be honest, I don't know how to win this one. Any ideas, Perry the Platypus?"

He nodded.

Candace watched disinterestedly as Phineas and Ferb battled the other giant robot. The pharmacist and platypus had disappeared at some point, probably off to find some impossible way of turning the tide back in their favor.

A vending machine broke into song and the giant robot joined in, while Phineas and Ferb provided commentary during the verses.

She couldn't quite hear the lyrics, but it sounded intense.

Suddenly the pharmacist started singing, too. He was also piloting a robot, though she couldn't see the platypus with him.

The platypus in question came out from under a table and ran around Phineas and Ferb's robot, tying up its legs. He threw a grappling hook up to the ceiling's rafters and tugged. The robot folded over on itself and collapsed.

The song continued, with Phineas and Ferb's friends joining in. They appeared to be conceding the battle.

"We'll win next time," she caught someone saying.

Candace got up from her seat, off to find Jeremy.

"Carl, what just happened?"

Isabella skipped giddily. The battle hadn't been part of her plan, but she'd still managed some time alone with Phineas.

She still could barely believe they'd lost.

Under the night sky, she made a solemn vow to find out who had beaten them and to subsequently destroy them in their next fight.

"Well," Heinz said, "that was fun, Perry the Platypus. Thanks for coming."

Perry chittered, smiling.

"I'll see you tomorrow, then? I have a few ideas for new Inators."

He gave a thumbs up and waved, switching back to mindless pet mode as soon as he was in sight of Phineas and Ferb.

"Oh, there you are, Perry."