Percy Jackson meets Harry Potter

Thalia

Harry and Hermione stood gaping at the girl who had just appeared in the rainbow. Floo powder was one thing but this? This was a little too weird.
"Can you tell those two to close their mouths please?" The girl snapped, shooting an annoyed glare at them.
Professor Chiron gave them a significant glance, and they both closed their mouths.
"Who are they anyways?" The girl asked.
"I'm Harry." Harry said in a dazed voice.
"Hermione."
The girl nodded.
"I'm Thalia." She then turned to Chiron, her electric blue eyes seeming to penetrate through the rainbow message. An Iris-Message, Chiron had called it.
"If Percy's been taken, we might be able to track him." Thalia reasoned.
"Last time, Hera took him," she said the name with utter disgust. Harry really didn't want to meet her if Thalia showed such contempt for her, especially considering all the horrible Greek nightmares that she would have seen.
"And we couldn't find a trail. But now, since he's just been taken by this wizard dude-"
"Voldemort, the most powerful dark wizard of all time." Hermione interjected. Thalia rolled her eyes.
"Yeah, yeah, Kelp Head's faced worse. Anyways, we should be able to track him this time. And I'm guessing that we'll find Annabeth wherever we find him. Oh, and that Rob guy too." She hastily added upon seeing Harry and Hermione's expressions.
"Ron." They automatically, simultaneously corrected her. 
"I'll be there in a few seconds." She said. Hermione and Harry stared blankly at her.
"Mrs. O'Leary's with her." Nico supplied, unhelpfully.
"Well thanks. That makes it about as clear as mud." Harry griped.
"Mrs. O'Leary is a hellhound." Prof- er- Chiron- said.
"She can shadow travel."
"But-?" Harry started.
"From America?" Hermione asked incredulously.
"Actually, I'm in Canada right now."
"But still!" Hermione protested. Thalia rolled her eyes. She waved her hand, and the rainbow message dissolved.
Suddenly, they heard a loud booming bark sound behind them.
"WOOF!" Everyone turned to look at the huge hellhound now filling Chiron's already crowded office.
"Yes." Thalia answered, now behind them. She was even more startling in person. Through the Iris-Message, they hadn't been able to see her jagged black hair, combat boots, Death to Barbie
T-shirt and... her silver, circular tiara? Somehow, that made her look even more imposing.
Her electric blue eyes were much more penetrating, and startling in person. She grinned and strode over to Nico.
"Death Breath." She said, and ruffled his hair.
"Pinecone Face." Nico countered, punching her playfully in the shoulder.
"Valdez." Thalia grinned at Leo.
"Grace." Thalia's expression darkened.
"Call me that again and you'll wish you'd never been born." She threatened, sounding extraordinarily serious. (Or Sirius) Harry and Hermione both gulped, noticing for the first time the bow and quiver strapped on Thalia's back.
Leo, however, just grinned and winked, shooting a fake finger gun at her. Apparently death-or-worse threats weren't uncommon for demigods to receive.
Thalia scowled at Leo a little longer, then rolled her eyes again and turned to Chiron. They embraced, which looked extremely awkward as Chiron was a centaur, and about twice Thalia's height.
"The rest of the Hunters are coming in a day or so. I came a little early so I could hang out with my cuz. Jason, Frank, Piper, and Hazel will all be here fairly soon. Frank and Jason are flying, Hazel's riding Arion, and Piper's riding Blackjack.
Leo snorted.
"I wonder who's gonna get here first." He remarked sarcastically.
Thalia smirked.
"Well judging by how fast that horse can run, and the fact that Hazel left a minute or so ago, I think she'll be here in an hour or so.
"An hour?" Harry asked incredulously.
"Yeah, I have to agree with Harry. That's pretty fast, even for Arion." Thalia rolled her eyes.
"Well, she's not coming from Camp Jupiter." She told them. "She's coming from CHB."
"Did you say Arion was a horse?!?!" Hermione asked unbelievingly. Thalia nodded.
"Yup. Fastest horse alive."
"What about the others? What are their names?"
"Frank, Jason, Piper." Leo answered promptly.
"Hazel will definitely get here first." He turned to Thalia. "So there's no point betting on her, but who do think'll be second?" Thalia pondered for a moment.
"Well, Jason's hugely improved his flying skills."
Harry and Hermione both did a double take.
"He's gotten pretty darn fast now, but I think I'd have to go with Blackjack. I don't think I'd ever bet against that pegasus, especially if there are donuts involved. So Piper will probably get here second."
"True, true. Blackjack is one wicked fast horse, but I'm fairly positive Jason's got the advantage this time. He's become a crazy speed demon. Plus, if he starts losing speed, he can always ride Tempest."
"Ladies, ladies, please." Nico interrupted, stepping dramatically between them, and spreading his arms out wide. "I think we all know who will win the race for second place." Thalia and Leo both raised an eyebrow.
"Frank, of course!" They exchanged disbelieving glances.
"Isn't he just turning into a bird or something?" Thalia asked skeptically.
Harry did another double take at that. Nico gave a mischievous grin.
"Oh, I wouldn't dismiss Frank's shapeshifting abilities quite so soon my dear cousins."
"Wait, am I even your cousin?" Leo asked. Nico shrugged.
"Who knows? Anyways, three Butterbeers at the Three Broomsticks says Frank arrives second. Losers pay." 
"Oh, you're on." Leo said, grinning wickedly.
"I don't even now what Butterbeer is," Thalia said, "but count me in."
Harry and Hermione stood agape, watching the banter. Chiron observed as well, but with a more amused expression.
"Actually, we'll make it..." Nico counted in the air, doing a few calculations in his head.
"Nine Butterbeers. Three for us, four for them, and two for Harry and Hermione." Thalia turned towards Harry and Hermione, evidently having forgotten them.
"Oh, yeah! Sure. You're on." They turned to leave the room, when Thalia stopped short.
"Oh, Zeus, what are we going to do about Mrs. O'Leary? She can't stay in Chiron's room."
"I was hoping you would reach that point." Chiron smiled. Mrs. O'Leary, who had been laying down very quietly, started wagging her tail at her name, causing the whole room to shake.
"I bet Hagrid would take care of her." Harry said, surprising himself. Hermione nodded vigorously.
"D'you think he'd be able to handle Mrs. O'Leary?" Thalia asked skeptically.
"Yes." Everyone else said at once. Thalia shrugged.
"I bet she'll get along well with Fang." Hermione pondered. Harry smiled.
"I reckon they'd get along quite well." He said, as they all walked out the door, Mrs. O'Leary following close behind.
As they walked down the corridors, they passed a blonde Slytherin. Malfoy. He slowed his walking as they passed, and gawked at the hellhound. She bounded towards him. He let out an unmanly whimper, and scrambled back, only to have Mrs. O'Leary jump on him, and coat him in dog slobber.
"M-Mrs. O'L-Leary!" Nico called, her voice trembling with laughter. "H-heel, girl!" Mrs. O'Leary obeyed, coming bounding back, and leaving a slimy Malfoy in her wake.
"You wait until my father hears about this!" Malfoy squeaked before running off.
"You know, he reminds me of Octavian." Nico said thoughtfully after he was out of earshot. Leo and Thalia burst out laughing.
"Oh, that would crack Percy up so badly." Leo said, wiping tears from his eyes, accidentally killing the mood. He realized what he'd just said, and scowled.
"Never mind. Let's just... go take Mrs. O'Leary to Hagrid's hut."
By the time they reached the grounds, they were all in a good mood again. Several people had done hilarious double takes on seeing the hellhound. Pansy Parkinson, Lavender Brown, Susan Bones, Neville, and, to Harry's delight, Crabbe and Goyle, had all screamed. One poor first year girl had fainted. Surprisingly, one of the ghosts had turned the corner, paled slightly, and whispered, "It's been a long time since I saw one of those.", and floated the other direction.
They were all laughing again, cheery-faced and grinning, when Hagrid opened the door.
"What're you lot doin' out here?" He asked. Then he saw Mrs. O'Leary.
"Aren't you a beauty?" He whispered, almost reverently.
Fang immediately started jumping all over Mrs. O'Leary. She in turn dropped to a playing position, tail wagging so hard it almost knocked Hagrid's door down. The demigods and wizards barely moved away in time as Mrs. O'Leary bounded through the door, just barely squeezing through, and knocking down all of Hagrid's possessions.
"She's called Mrs. O'Leary." Thalia informed him.
Hagrid was so overjoyed that he didn't even notice the face that he'd never seen Thalia before today.
"Eh? Wonderfull name, that." He responded absently. Harry and Hermione grinned. They knew Hagrid would be thrilled once he saw the hellhound.
Suddenly, a burning smell reached their nostrils. Hagrid, completely oblivious, closed the door, forgetting all about the kids outside.
They turned, and suddenly, a blur shot through their visions, then, a girl with wildly disheveled, frizzy hair climbed off of a panting horse. The girl knelt on the ground, picking something up, and then fed it to the horse. She then bounded towards the group, looking excited.
"That was fun! It's also the quickest Arion's ever run I think." The horse snorted, as if to say: That? That was nothing! I could run twice that fast with my eyes closed.
At least, that's what Harry would interpret it as.
"Hazel!" Thalia, Leo, and Nico all ran over to hug her. Hermione stood gaping.
"That... that... that was incredibly fast!" She said. Hazel smiled shyly, and Arion shook his mane proudly.
You know it.
Harry guessed he was conveying.
"C'mon, let's go into the forest while we wait for everyone else."
"The forest?!?!" Harry and Hermione shouted in unison.
"B-but it's super dangerous in there!"
Leo grinned.
"All the better. We probably need a little bit of training." Harry and Hermione exchanged helpless glances, but followed the completely insane demigods as they walked into the Forbidden Forest.

A/N
I realize, I forgot to put an author's note at the end of the last chapter. I don't think anyone minds though. ;)
Wow, Chapter 16. This book's going by so fast!!!
Thanks for reading everyone!!!!!!
I'm sorry I'm not the fastest updater, but I'm working on about 7 other stories at the same time, so please don't think of my slowness as me not being dedicated to this story. :)
I won't be stopping this story anytime soon I hope, so just be patient with my slow updates. 😜
Thanks AGAIN for reading!!!!!!!!
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