Disclaimer: Rick Riordan owns Percy and co., not me!

There was nothing quite like Central Park on a warm, sunny day. The park was so far from their small, dingy apartment that Sally rarely took her six-year-old son there. But the stars had aligned on that day; the gods seemed to want Sally to bring Percy to Central Park. It was a weekend at the end of May during the first beautiful stretch of weather Manhattan had seen yet that year. It wasn't too humid, the bills were paid (well, most of them at least), and all Sally wanted to do was get outside.

Percy was thrilled. She had brought a large bag with sandwiches, drinks, a baseball, and Percy's beaten up secondhand glove. They were planning on having a picnic and then playing ball for a little while. Percy's face had lit up when Sally suggested it; these days, she was usually either working or too tired from working for outings like this.

After bouncing around the park looking for the perfect spot to eat, Percy finally decided on a shady span of grass where there weren't that many people nearby. Sally was barely sitting down when he grabbed her bag and pulled out two peanut butter and jelly sandwiches. She didn't think that he would be able to keep himself still long enough to eat it.

After his first bite: "Mommy, can we play now?"

"Not yet honey. Finish your sandwich first." He stuck out his lower lip in a cute little pout and took another bite.

"Mommy?"

"Yes Percy?"

"Are you going to tell me that I have to wait a little after I'm done eating before we can play?"

"Yes, Percy. You don't want to get a bellyache, do you?"

He shrugged. "I guess not."

He took another bite silently. "Can you tell me a story?" That was actually a good idea. It would keep him quiet and calm long enough to finish eating and digest a little before he ran around.

"Sure honey. What do you want to hear? Goldilocks? Cinderella?"

He scrunched up his face. "No more fairy tales. Tell me another myth."

She was hesitant to expose Percy to any more myths than she already had; she knew that he would certainly hear enough of them in a few years to last a lifetime, but then again maybe hearing them now would prepare him better for his life as a half-blood.

Percy loved hearing stories from her. She started off with the typical fairy tales and stories that most moms told their children. But she ran out of them quickly – he asked for so many – and she told him a Greek myth in a panic. He loved hearing the myths and asked for them very frequently.

"Of course Percy." She sifted through her memories trying to find the most kid-friendly one she could that he hadn't heard yet. Unfortunately there weren't many. She settled on the story of Hercules; she had already told him parts of the whole thing, but usually it was a bedtime story that he couldn't stay awake for.

He finished his sandwich before she was done telling him about Hera's anger at Hercules and tricking him into hurting his family. When she started telling him about all of the tasks Hercules had to complete in order to make up for it, Percy's mouth dropped open in astonishment. He was completely enraptured by the eight tasks – Sally couldn't quite recall all thirteen despite extensively studying Greek mythology a few years earlier.

When she was finished telling him about all of the monsters that Hercules had to face, she thought for a moment that Percy was about to drift off to sleep. But when he heard her stop speaking, his eyes popped back open.

"That was a good story Mommy. Can we play now?" Sally rummaged through her bag and pulled out Percy's ball and glove. He ran away from their things to get into position. While Sally stood up, he enthusiastically threw the ball up into the air and tried – and failed – to catch it. The boy couldn't stay still for more than a few seconds, unless of course he was listening to one of Sally's stories. Poseidon had said that Percy might be diagnosed with ADHD one day, and she was definitely beginning to believe it.

He threw the ball to her and she caught it easily. Then she gently lobbed it back to him. He missed and had to bend over to get it. They tossed it back and forth a few times before Sally noticed something out of the corner of her eye.

"Did you see that? I caught it!" Percy was thrilled.

"That's great honey." But her attention was on the large dog watching them. Its head had been following the ball back and forth and back and forth. It was a large black dog, larger than any mortal dog should be. And its eyes were glowing red.

Percy noticed her distraction and followed his mother's eyes to the hound.

He gasped. "A puppy! Mommy, can I go pet it?"

"No Percy!" she said sharply. She motioned for him to come back to their picnic site. As he walked, Sally saw a young couple pass by the hellhound. The girl pointed at it and gushed, clearly thinking it was cute.

The Mist. Sally had always been able to see more than anyone else around her, and she remembered Poseidon telling her it was because she could see through the Mist.

"Percy? What kind of dog is that? What do you see?" she asked out of curiosity.

He looked at it again.

"A white one. It's really little and looks so soft. Why can't I pet it?

"You should never pet stray dogs," Sally responded, never removing her eyes from the hellhound. How could everyone else be mistaking that huge creature of Hades for a cute white puppy? "They may look friendly, but you don't want to get bitten. Never pet a dog unless the owner says it's friendly."

Then Sally remembered something else about Poseidon. It was so long ago, she was beginning to forget some of the things that he told her. She remembered once why he never called any of the mythological creatures and gods by name, instead using phrases like "my brothers" and "the Kindly Ones." He told her that names had power and tended to attract the wrong types of beasts.

The hellhound must've come because of Sally's Hercules story. She looked around quickly. What other monsters may have been in the area and decided to come?

"Percy, let's go home now," she said.

"But we barely played at all!" She knew he wouldn't want to leave yet. But she couldn't just wait here for the rest of the monsters to join them.

"Well how about this: let's stop to get ice cream on the way home. Sound like fun?"

He smiled widely. "Yes!" He went to collect their things. She knew that ice cream would convince him. She was never able to afford treats like that. She probably couldn't afford it now, but she needed to get Percy out of the park.

Sally grabbed her young son's hand and walked towards the park exit, all the while paying as much attention as she could to Percy's chatter.

They had passed monsters in the past before. Heck, Percy had already killed a pair of snakes that decided to drop into his crib. Other than that, they were never attacked. Percy still remained ignorant to the existence of monsters, and she wanted to keep it that way.

Something about this hellhound had really shaken her up. Maybe it was how it just sat there watching them. Or maybe it was knowing that she, Sally Jackson, had unintentionally summoned it.

As Percy got older, the monsters were appearing with greater and greater frequency. Sally knew that someday, a monster would come that wouldn't just sit and watch them, and then she would be helpless trying to defend her little boy.

She needed to find a way to keep the monsters away from her and Percy once and for all.