Disclaimer: I do not own Percy Jackson

Perseus Jackson, ten year old demigod unaware of his heritage, was currently at the park with his dog doing his best to teach it something that wasn't particularly violent. Percy had noticed quickly that Mrs. O'Leary was quite intelligent for a puppy.

Mrs. O'Leary never ran away from him, yet knew that she couldn't be with him at school when he calmly explained it to her. But she was always waiting for him the moment it let out, despite the fact that he had left her inside the apartment.

The first time he had seen her waiting outside his school he had expected her to have somehow opened the door. Percy had been worried that they would be robbed, something they couldn't afford to let happen.

So Percy had rushed home, dashing through traffic, taking the fastest route for him. Mrs. O'Leary managing to keep up with his parkour and inhuman running speed with relative ease.

When Percy saw his apartment he expected a wide open door, but only saw a closed one. The apartment was exactly how he left it, not a thing out of place and the door was still locked.

Percy had been stumped but decided not to look into it, he didn't care enough. If Mrs. O'Leary could somehow get outside and meet him at school he would be glad to see her!

Sadly, that's just the first of a series of problems that came from owning his strange new dog. Mrs. O'Leary was quite trainable, but she could have quite a few violent tendencies.

Percy had stopped buying her toys because she would tear through them in moments. Plus she enjoyed hunting small animals for food. She refused to eat any type of dog food and preferred meats. Sally had taken to buying chicken in bulk since it was cheap.

Percy had 'accidentally' taught Mrs. O'Leary how to attack on his command. At least that's what he told his mother. But in reality why wouldn't he want such a badass dog that would fight for him?

Percy never ordered Mrs. O'Leary to attack anything other than trees and bushes, but she knew how to and that was enough for him.

But sadly Mrs. O'Leary seemed more inclined to aggression then normal. She would growl at those she didn't know and chase and attack all sorts of animals. Percy was doing his best to curb the aggression to varying results. He'd gotten her to stop growling at people but if another dog barked at her or she saw a squirrel she'd go ballistic!

Percy could keep her under control though for the most part, and she WAS smart. He had trained her to do all sorts of tricks, and she picked them up fast.

Despite her aggressive tendencies and Houdini-like abilities to escape locked houses, Percy loved her to death. She was his first and only friend and she didn't judge him. They would run through the city together boy and dog, hopping and dodging and climbing all manners of obstacles. Mrs. O'Leary was great at keeping up with him she hardly had to try.

"Alright girl now play dead!" Percy ordered her. Mrs. O'Leary stared back at him unwaveringly. Her strange looking eyes blinking in confusion.

Percy facepalmed with a resounding smacking sound. He looked back at her and said,"that's when you roll on your back like this," Percy demonstrates falling and rolling over on the snowy ground. "Then stick your tongue out," sticking his tongue out, "and wet your bwody gwo limp." He said the last part in jumble due to his mouth sticking out.

Mrs. O'Leary responded by jumping on him and licking his face. Percy laughed and tried to throw her off but she was quite persistent. And they rolled around in the snow getting themselves wetter and wetter.

Percy would wrestle her and play fetch and laugh as she chased squirrels. He had never been this happy. It was difficult sometimes but in the end it was totally worth it.

—

Eleven year old Percy had a small problem, well more like big problem. His dog was way too big. She just didn't fit in the small apartment he and his mom were living in. She had gone from the size of a large dog to the size of a horse.

They were currently laying down in the grass of a nearby park basking in the warm summer heat. Percy had his hands crossed behind his head lying on his back staring up at the clouds. Mrs. O'Leary lay next to him resting her head on his stomach.

"I don't know what to do Mrs. O'Leary! Mom can't afford a bigger apartment and I wouldn't ask her for one anyways. But you don't fit anymore! I don't just wanna leave you outside…" Percy vented to the hellhound.

Mrs. O'Leary responded with a whine. "I just can't leave you by yourself! We're partners! I would never leave you behind!" Mrs. O'Leary responded with a bark and a growl.

"I know you can take care of yourself! But I don't want you to. What if you decide you like being outside and wanna leave me," Percy's voice had turned apprehensive and sad.

Mrs. O'Leary growled at him. Percy stares at her for a second with slightly watery eyes. "You're right. I'm dumb. You wouldn't ever leave me. Just like I won't leave you. We're partners!" Mrs. O'Leary jumped on her feet and excitedly started bouncing around Percy. Kicking up grass and making loud stomping noises while she yipped excitedly.

Percy laughed and stood up himself. "Ya let's go for a run girl! That sounds like fun!"

—

Percy sat in class listening to a lecture by his Latin teacher Mr. Brunner. Mr. Brunner has a scraggly brown beard soft brown eyes and was one of the nicer teachers their. He was also paralyzed from the waist down but that didn't seem to affect him much.

Percy was doing his best to try and listen to the boring lecture out of respect for Mr. Brunner but was still sadly failing. That's ADHD for you, always making his life difficult.

"Percy, are you paying attention?" Mr. Brunner suddenly asked him.

"Uh… yes I was sir." Percy responded a little belatedly.

"Well then, who was the Ancient Greek god of the sea?"

Percy sighed in relief because he actually knew this one, "Poseidon, sir."

Mr. Brunner gave him a deep searching look, "very well, do make sure you stay with the class this time Percy."

Half the class snickered but the rest weren't paying attention. Most of them were delinquents too, they were sent to Yanch academy by their rich parents so they wouldn't have to deal with their behavior.

Percy turned over to his friend Grover, a thin boy with crutches and whole beard at the age 12, and noticed he had fallen asleep. Percy sighed and turned back to the front of the class realizing he wouldn't be able to wake him up.

The bell rung and Percy stood up slinging his backpack onto his back as Grover snorted and opened his eyes. "Remember class the field trip to the museum is tomorrow so meet at the front gate at 8 sharp!" Mr. Brunner helpfully reminded them.

Latin class was their last class for the day so now they had free time to do what they wanted on campus. Percy did what he always did he went to the outer parts of the campus where the woods started.

As students they weren't allowed in the woods but Percy had a rebellious streak and a reason to not care. Anything dangerous in the woods wasn't nearly as dangerous as the reason he was there.

And as Percy crossed the first trees into the darkness of the woods he gave a sharp whistle. He was rewarded with the sinister sight of glowing white teeth and burning red eyes coming from the dark shadows of the trees in front of him. The teeth and eyes came forward and a shape formed around them seemingly melting out of the shadows.

It was the form of a large dog the size of a pickup truck with claws the length of kitchen knives. It was slender and you could see the strong tense muscles under it's midnight colored fur.

It was a terrifying sight for anybody else but to Percy it was the exact opposite. "Hey Mrs. O'Leary! Did you miss me? Did you miss me?" He asked her in a cooing tone as he reached out and scratch her head. Which she lowered to give him better access before rolling over so he could give her a belly rub, panting happily.

"We're going on a field trip tomorrow girl! Are you excited? You'll finally see something that's not these woods!" She jumped up happily and howled to the sky. A loud ominous sound that seemed to rip into the air itself. Percy laughed and joined her himself. He loved howling with her.

Percy's howl wasn't as loud but it sounded just as animalistic. It wasn't ominous but it had a grittier sound to it. Mrs. O'Leary cut off her howling and tackled him to ground ready to play. He gave an oomph sound as he got tackled.

"Oh you wanna wrestle again girl? You ready to lose again? What's the score 5-3?" Mrs. O'Leary gave an indignant little yip to the question. "Oh I forgot! My bad it's 5-4," Percy laughed at her from below her massive paw resting on his chest.

Percy suddenly placed his hands behind him and his fleet flat on the floor and pushed with all his strength. Lifting himself off the deck and escaping Mrs. O'Leary's paw Percy shot up to a tree branch above him.

Mrs. O'Leary gave a startled bark as he grabbed the branch and swung himself around it so that he was standing on it. Looking down on her as she stared up at him they both squinted their eyes. She gave a powerful bark and jumped at him. He leapt to the side reaching to a higher branch and grabbing hold. Mrs. O'Leary destroyed the branch he had been standing on and slammed into the tree before pushing off it at him again.

He swung himself up and around using his momentum to throw himself like a dart at the rapidly approaching dog. He hit her right in the midsection and tackled her to the ground. They broke through the foliage around them to the ground and landed with a loud crash. He climbed around her until he had his arms around her throat and began choking her out.

The demon slapped her paw against the ground three times and Percy let go. "Make it 6-4!" Percy laughed at her. She growled at him and ran deeper into the forest. "No! Mrs. O'Leary come back!" He laughed and chased her.

Later in the day Percy was getting ready to head back to the school because curfew was coming up. "Alright Mrs. O'Leary it's time for me to go again, if you want to come with me tomorrow you better hop in now." Percy told the demon-dog. She responded with a wood before leaping into Percy's shadow seemingly melting into it.

Percy's shadow went from his shape and form into that of the hellhound he wasn't worried though. He knew from experience that no one would notice anything different Mrs. O'Leary was cool like that.

As Mrs. O'Leary settled in Percy noticed the usual changes that came with her joining his shadow. His eyesight became heavily enhanced and his teeth grew sharper. His sea green eyes had a blood red outline around the pupil and his hair grew a little longer and wilder. His already longer than average nails became even more claw like. And to top it all off he felt much stronger.

Percy found his dog's abilities and size strange but he knew better than to question it. He knew his mom knew and would tell him when she was ready.

And with that Percy ran off in the direction of school with the intention of being on time for curfew. He had a field trip to go on tomorrow and he didn't wanna miss it because he got in trouble right before.

AN: I was gonna include the actual field trip itself but I decided it'd be better to have that whole experience go off on its own chapter. So here's basically some background Percy and dog moments.

Percy will be shown going through most of the events of the book in obviously different ways it'll probably even completely diverge at a certain point. He might or might not tame anything else for a while depends on how I'm feeling. The pairing is still unknown if there even is one since romance is not my best skill.

Anyways hope you like the chapter! Please leave a review with ways to improve if you noticed something! Other then that feel free to leave any bitches, moans, and complaints. Or just positive feedback in general.