A/N: Hey there, Ivy here! I've been working on this fanfic for a while, and by a while, I mean a majority of my high school years. Except, I finally have the confidence to actually publish it. This is going to be a crossover fanfic. The only reason why I'm not putting it in the crossover section is because, well, let's be real, nobody ever really goes in the crossover sections. The main crossover is between Percy Jackson/MCU, but I'm thinking of bringing in Gravity Falls and Supernatural into it. Let me know if you guys are okay with that in the comments. Okay, on to the story!

Chapter One: Nothing is What it Seems to Be

My twin brother and I sat outside the Museum of Natural History, in Manhattan's Upper West Side, with the rest of our fifth grade class from P.S. 116, eating lunch in the nearby park before we went in to the museum.

"You ready to go see some dusty old relics that probably have a better security system than our apartment?" asked Jamie, stealing some of my cookie.

"What security system?" I asked, stealing in turn, some of his gummy bears.

"Exactly," he replied, with his mouth full of my cookie.

"All right kids, finish up!" said our teacher. I turned from Jamie to our teacher, Mr. Tarragon, who was walking around our circle of benches, making sure that everyone was indeed packing up. "We were supposed to be inside ten minutes ago!"

Mr. Tarragon was probably in his mid-twenties. He had a full beard, and always wore a burgundy colored beanie that covered most of his curly, dark hair (despite there being a school rule that did not allow hats to be worn on campus).

When he walked toward us, he did so with a limp, which he said that he got because of a boating accident. It wasn't that noticeable, but when it got really bad, he would rely on his cane most of the time.

"I've still got my bag of chips," I said sadly, to Jamie. Mr. Tarragon had warned us that food was not allowed in the museum because the curators apparently did not want our chubby, greasy hands touching the glass displays.

"Stuff them all in your mouth," he replied, reaching for my bag. "I'll help you."

"Pines twins! You two ready?" Mr. Tarragon asked as he came to our bench.

"Yessir!" Jamie said, with his mouth full, having stuffed it with most of my chips. I also nodded, because unlike Jamie, I could not talk and eat at the same time. I was sure that something would spill out of my mouth if I tried. Mr. Tarragon let out a rather exasperated sigh.

"Kids, you don't have to eat that fast. You two look like you're gonna have a heart attack."

"You said no food in the planetarium," I pointed out, after I had swallowed.

"Yes, yes I did," Mr. Tarragon said, nodding. "However, I didn't say no food in the hallway, did I?"

Oh.

I hadn't thought about that. I recognized the realization on Jamie's face, as he too, realized what our teacher was saying. We followed our class into the Museum of Natural History as I happily finished my bag of chips with Jamie.

I'm pretty sure that Jamie had fallen asleep during the planetarium show. I had felt his head resting against my shoulder at one point.

"Alright kids, I hope you remember the names of the planets in order because we're having a quiz on Monday!" Mr. Tarragon said, after we had re-grouped, looking far too cheerful about the prospect of a quiz. There was a collective groan from the class, with Jamie and I included.

"Actually, we got another half hour before the bus gets here. How about you guys split into groups, and wander around the museum for a bit? We'll meet back here in twenty minutes."

The class scattered.

"Who lets their class of ten-year-olds go wander around a museum by themselves?" I asked Jamie, as he grabbed me by the hand and dragged me to the dinosaur exhibit.

"Who cares? Let's go see those huge dinosaur bones! Some of them are bigger than you and me stacked on top of each other!" he replied, making a beeline for the T-Rex skeleton.

We got bored with the dinosaurs.

"All they do is sit there," Jamie complained, and I agreed. We decided to do what Mr. Tarragon had suggested: wander around.

Eventually we ended up in the very empty Hall of Mexico and Central America, where there were two teenage girls whispering to each other by some jewelry from the Maya. They stopped when we came in, glanced at us, and continued whispering.

"Weird that there are hardly any people in here," Jamie whispered to me. "The rest of the museum is packed."

"Maybe people don't find this section interesting," I replied. "Besides, there's three floors to this museum."

This time I led the way, holding on to Jamie's elbow, as I steered him away from trying to escape.

"Hey, do you know what time it is?" I asked Jamie. He shook his head in reply.

"Probably time for us to start heading back though. We spent a while with the dinosaurs."

"I'll go ask them," I replied, pointing to the teenage girls who had moved on to the Aztec's. "If they don't have a watch, they probably have a cellphone."

"Excuse me," I asked as I approached them. They turned toward me, somewhat surprised that a little kid was talking to them. "Do you know what time it is?"

One of the girls looked like she could be a movie star. She had long, blonde hair, and really bright blue eyes. The other one was just as pretty, who had light brown hair that looked almost red in certain light.

"Sorry, I don't have a watch," replied the girl with the blonde hair. "But Keris here has a cellphone,"

"But we don't need one, do we?" replied the girl with brown hair. "Because we both know exactly what time it is."

"Lunchtime," they said at the same time, with smiles that made my stomach sick.

Wait, lunchtime?

One of the girls, Keris, I think, took a step forward. On instinct, I started backpedaling. I didn't like the way either of them had been looming over me.

"Oh, come now, demigod," one of them said. "Just one little bite."

Demigod? Bite? What were they talking about? Where was Jamie?

I hadn't been paying attention to where I was going when I'd been backpedaling from them, and I bumped into a display case that was in the corner of the exhibit. The teenagers used my confusion to their advantage, and blocked off my exits.

"Hey jerks! Eat this!" Jamie shouted from across the exhibition floor, chucking an object at them. It landed several feet away from us.

"Deal with him," the blonde one said to Keris.

"Now, what to do with you?" she said to me, grabbing my arm. I twisted my arm, trying to wrench myself free, as her nails dug into my skin. She smiled at me, revealing sharp canines.

I was panicking now. She and her friend were probably vampire-wannabes who were taking their obsession way to far. I couldn't see how Jamie was doing, because Vampire-Wannabe No. 1 was blocking my view. I hoped he was okay.

"Let me go!" I yelled, squirming in her arms. She just glared at me.

"Let's take this somewhere quiet," she said, dragging me toward a 'Staff Only' door. I wanted to point out that we were in a quiet area already, and that the only people around were her vampire-wannabe friend and my brother, but I figured that that wouldn't help my case. I kicked at her as she continued to drag me to the door, and was surprised when I heard a metallic sound instead of my sneaker hitting her shin.

"Alright, that's it," she growled, wrenching the door open, and throwing me into the janitor's closet. My head banged against empty cans of paint, and she slammed the door behind her. I heard the lock click. I didn't even know that janitor's closets even had locks. Seriously, were a couple of cans of empty paint, a mop, and a broom even worth locking up?

"Hey! Let me out of here!" I shouted, banging on the door. I heard commotion from the hallway; something glass crashed to floor. "Jamie!"

Not long after the commotion, I heard footsteps coming toward the janitor's closet. Scared that it might be the Vampire Wannabes, I grabbed the broom, holding the wood end in front of me, like a sword, the end pointed at the door, ready to give whoever came through the door a really big bruise.

The lock clicked open, and slowly, the door handle opened.

"Yaahh!" I shouted, thrusting the broom handle forward, not really paying attention to who was on the other side of the door.

"Woah there kid!" someone shouted, sidestepping my broom, and grabbing the hood of my sweater before the momentum could make me crash face-first on the ground.

"Let me go, you crazy vampire wannabes!" I shouted, waving the broom around wildly, hoping that it would hit whomever was grabbing me.

"Alright, that's enough of that," they said, yanking my broom from my hands. I lifted up my arm, trying to grab my hood to escape. "Kid! Calm down! I'm not going to hurt you."

Eventually, I realized that the person who had freed me from the janitor's closet was not one of the vampire wannabes, but my teacher.

"Jenny!" I heard Jamie shout. He had a big, red scratch on one of his cheeks, and his hair was even more messy than it had been. "You okay?" he asked, putting a hand on my shoulder.

"I think so," I replied, grabbing the outside of his pocket of his sweater. My heart was beating a mile a minute, and I was still freaked out about the fact that I'd gotten attacked. Having Jamie near me helped calm me down a bit. "What about you? Does it hurt?" I asked, gesturing toward his scratch.

"It's not that bad," he said, shrugging. He then turned to Mr. Tarragon. "What were they?"

Mr. Tarragon shrugged. "Nobody. Probably just some crazy teenagers with an overactive imagination."

It was then that I noticed the bronze dust scattered across the museum floor. I wasn't sure what it was, but it seemed important.

"They were going to eat us!" I shouted, waving my arms for emphasis.

"Don't be ridiculous kid-"

"I kicked one of them and her leg didn't sound normal."

"And she called us demigods. What's a demigod?" Jamie chimed in.

"We'll discuss this later, with your parents. In the meantime, I need to get you two home," Mr. Tarragon said, ignoring our protests. "Seriously kids, this is a discussion that is better to have with your parents."

A/n: All right, that's the first chapter! I have no set schedule yet as to when I'm going to be updating this- finals are next week, and while I may not be studying for them, I do have a lot of projects due in the next few days. You can expect an update sometime in the middle of next week. Let me know what you think so far! Any constructive criticism is welcome!