This was partly very loosely inspired by the "How It Should Have Ended" videos on YouTube. Go check those out, if you haven't heard of them already!
I don't own anything, all credit goes to Rick Riordan.

How Percy Jackson and the Olympians Should Have Ended

"That's him," said Percy. "That's Typhon."

"No," said Chiron. "That's our good friend Leroy! He's here to help us!"

"Really?" asked Percy excitedly.

"No," said Chiron, pointing out the door, which was open for some reason. "That is our good friend Leeroy. Leeroy Jenkins, to be exact."

Percy looked outside to see a guy from the Apollo cabin running in circles, waving a sword like a maniac.

"Oh," said Percy.

"Just a little bit farther," said Luke. "I promise." Just then, they arrived at a street, across which stood the Castellan household.

"Can we pleeease come with you, Luke?" asked four-year-old Annabeth, giving him the puppy-dog eyes. "Pweeeeeeeaaaase?"

"No," said Luke, forcing himself not to look into the huge, bulging, tear-filled, four-year-old eyes. "No, I'll just get some stuff and-"

He was interrupted by a flash of golden light lighting up the area.

"LUUUUUUKE," said a deep male voice. "I AM YOUR FAAATHER!"

"ROOOOOOOAAAAAAARRRRRRRRR!" roared the Minotaur, which probably meant, "I'm Norm!"

"Well, Norm," said Candace of the Apollo cabin, whose helmet had Celestial bronze snakes sticking out of it, giving her the look of a gorgon, "Feel the wrath of my platypus!"

Candace pulled a full-sized, blue-green platypus out of her pocket and threw it at Norm. While the platypus was zooming through the air, he got a fedora out of nowhere and slapped it on his head, then landed on the ground with precise precision, then jumped around, kicking, punching, tail-slapping, and even karate chopping monsters this way and that. The impending awesomeness caused by his attacks emmited a flash of bright yellow light.

"My eyesssssssss!" cryed a dracanae.

"He'sssss too awessssome!" cried another.

"Leeroy," said Michael Yew, "You may now proceed."

Two campers, who had been holding Leeroy back by the arms, suddenly let go, and leeroy charged into battle shouting "LEEEEEERROOOOYYY JENKIIIINNSSSSSS!" as he sliced monsters this way and that.

"Well, that sure was a lot easier than having Percy come over here and break the bridge," said Michael.

"You got that right," said Candace.

"So tell me, Ethan," said Kronos. "What else happened on the brigde today?"

"I.. Um… I'm not entirely sure, sir," said Ethan nervously.

"TELL ME, WHAT IT IS, ETHAN!" shouted Kronos, grabbing Ethan by the collar of his shirt and dragging him forward. "TELL ME WHAT THEY DID THAT INCAPACITATED ALL MY MONSTERS!"

Ethan gulped. "I think it was a… a platypus."

"You cannot imprison me!" shouted Hyperion. "but just in case, I had a daughter some fourteen years ago, you should probably go check that out sometime soon."

"Yeah, like we're gonna believe that," said Percy.

"But it's true!" complained Hyperion. "I swear! I-" Then his face was completely encased in wood.

"You," said Grover, "Are a very nice maple tree."

He was interrupted by a strange noise.

"REEEEEET!" shoted the giant evil flying pig. "REEEEET!"

"Oh no!" said Annabeth. "No hero has ever killed that before!"

"Well that's about to change," said Percy. "Grover, get Candace from the Apollo cabin and tell her to bring her platypus. Annabeth, get your sister Simone and tell her to bring her magic potions."

"We're on it!" shouted Grover and Annabeth, running off in different directions.

Percy smiled. "We've got a pig to catch."

"Behold, evil flying pig," said Percy, sticking the dragon potion into the platypus's mouth. "PERRIBLE THE DRAGONPUS!"

Nothing happened.

"What is it?" asked Percy. "Why isn't it working?"

"Well," said Simone. "It's possible I may have miscalculated the-"

Before she could bore them with an over-complicated science-y thing, there was a huge poof of pink dust, and from it appeared a horrible dragon-platypus hybrid-monster!

It had tough, blue-green scales, sharp teeth on its yellow-orange platypus bill, yellow-orange spikes on its back, sharp claws on all its limbs, two of which were probably venomous, and a yellow-orange beaver tail at the end of its blue-green dragon tail.

"REEEEEEEEET!" shouted the flying pig.

"GRRRRRRRRR!" shouted the dragon/platypus.

Perrible opened up his blue-green dragon wings and flew up to the pig, ripping it appart with his claws.

"Ah, Candace, where would we be without you?" asked Percy.

"What about me?" asked Simone.

"ROOOOOOOOOAAAAAAAAAAARRRRRRR!" roared the drakon.

"GRRRRRRRRRRRRRRRRRRRRRRR!" growled the dragonpus.

Perrible flew up to the drakon, which was three stories above him, and pulled his arm back to punch it in the face, when suddenly! The drakon opened its mouth and a torrent of acid hit the dragonpus in the face!

"NOOOOO!" shouted Candace as the monster fell onto the ground in an acidic, burning heap. "PERRIBLE!"

"Well, so much for that," said Percy. "I guess I'll kill it.

"Or I will!" shouted the girl who was dressed as Clarrisse.

Several scenes too sad, awesome, and/or epicly amazing to parody later…

"Thalia Grace, my own daughter and leutenant of the Hunters of Artemis," said Zeus.

Thalia walked forward. Or, rather, crutched forward, as both her legs were broken.

"As reward for giving us a fighting chance in this battle," said Zeus, "We will fully heal your legs. Apollo?"

"Done," said Apollo, snapping his fingers.

Immediately, the casts around Thalia's feet broke in half and fell off of her now fully-healed legs.

"Yaaay!" shouted Thalia, throwing her crutches in the air and running a victory lap around the throne room.

"Hera, on the other hand," said Zeus, "Will get a serious time-out and a stern talking-to for breaking your legs."

"Yaaay!" shouted just about every demigod, and Hera huffed.

"Also," said Artemis, once Thalia had stopped running, "All the Hunters that died this week will go to Elysium. Right?"

"Yeah, sure," said Hades nonchalantly.

Artemis gave him one of her signature death glares, which worked pretty well, considering it belonged to a twelve-year-old girl.

"Fine," said Hades. "I'll streamline their application."

"Tyson of the Cyclopes, son of Poseidon," said Zeus. "For leading the Cyclopes in chaining up Typhon, we will give you not only a new stick, but also a year's supply of peanut butter!"

"Yaaay!" shouted Tyson, jumping up and down with excitement.

"Annabeth Chase and Simone Robertson, my own daughters," said Athena. "You two have gone far beyond our expectations. Am I right?" She looked around the room.

The other gods murmured some halfhearted words of agreement.

That was apparently enough for Athena. "For doing so, you two are now Official Architect and Official Scientist of Olympus, respectively."

"Yaaay!" cheered Annabeth.

"Wait," said Simone, "What exactly does an Official Scientist do?"

Athena was silent for a moment. "I hadn't thought of that…"

"Some wisdom goddess," muttered Simone under her breath.

"Candace Flynn, daughter of Myself," said Apollo. "For making this battle a thousand times easier, I hereby dub thee Most Awesomest Person in the Universe, second only to me, of course."

The other gods rolled their eyes.

"And also, a statue of Perrible the Dragonpus will be built on olympus in his honor. Right?"

Annabeth shrugged. "Sure, I guess."

"Don't make me turn you into a snake," said Apollo threateningly.

"Fine," said Annabeth. "I swear to build a statue of Perrible the Dragonpus on Olympus."

"Oh thank you, thank you, thank you!" shouted Candace, running over and giving Annabeth a big hug.

"Oh, can you make a statue of me, too?" asked Aphrodite.

"And me!" said Ares.

"Heck, why leave me out of the picture?" asked Apollo.

"PERCY JACKSON!" interrupted Poseidon.

Everyone quieted down as Percy stepped forward.

"For no other reason than being the main character," said Zeus, "You will be given one wish."

"One wish?" asked Percy.

"We know what you'll say," said Zeus, "Force us to pay more attention to our children…"

"Are you kidding?" exclaimed Percy. "IMMORTALITY FOR DA WIN!"

But then, Percy looked over at Annabeth's distraught and distressed face.

"I mean, um, I change my mind, you have to swear on the Stix that you'll pay attention to your children."