This is a bit on the short side, but it's only the exposition. Future chapters will be longer.
As the songs don't fit the show exactly, I changed them accordingly. But I'm trying my best to incorporate them into the story.
Have fun :D

"What are you doing, mommy?"

Maddie Fenton turned around to see the small form of her six-year-old son Danny standing in the doorway to the lab.
She'd been working on a new weapon to absorb ectoplasmic energy from ghosts. It was something she and her husband Jack had planned for a while now. A small side project to their work on the ghost portal.

Maddie set her screwdriver down on the worktable and hurried up the steps, kneeling in front of her son. She took off the hood of her hazmat suit to look Danny in the eyes.
"What are you doing here sweetie? You know you and your sister aren't allowed in the lab."

Danny clutched the green ghost plushie in his arms closer to himself. It was a gift Jack had gotten him for his fourth birthday.

"But mommy, you promised to tell us a story tonight." His lip trembled slightly and Maddie sighed. She had forgotten about that.

"Oh Danny, I'm so sorry. I was just busy..." She gave him a quick hug before pushing him to the door. "Why don't you run up to your sister's room, mama will be there in a minute."

The six-year-old beamed. "Okay!"

o.o.o.o

Maddie made herself comfortable on the edge of her daughter's bed. Jazz herself was nestled between the pillows, nose stuck in a book. The mother could vaguely make out the title and surmised it was another text about psychology.
She knew her oldest disliked being interrupted while reading, so she turned to address the boy in her lap instead.

"What story do you want to hear tonight, sweetie?"

Danny shoot up in a second. An excited gleam entered his blue eyes. "Can you tell us a story about ghosts?!"

Hiding behind the pages of her book, Jazz rolled her eyes. Great. Another misadventure of her parents' time in college. It was absolute nonsense. Ghosts didn't even exist.
Besides, she was way too old for bedtime stories. Her only reason for being here was Danny. Jazz liked to see her little brother happy, even if she had to endure listening to stories about floating dead entities.
So when she noticed her mom staring at her from over the book, Jazz gave a slight nod.

"I don't mind."

"Oh well, then let me think for a moment.", Maddie said.
Usually, her husband would be the one to retell any kind of ghost fables and hunts they'd been on in the past. However, Jack was out on a ghost convention, so the nightly duty of entertaining their kids, mainly her youngest, fell to Maddie this time.
She wasn't good at telling stories. There was one, though, she knew by heart.

The mother looked at her kids, a smile slowly building on her lips.

"Do you know the legend of the Antra Elementorum?"

Danny was bouncing on the bed, shaking his head vigorously. Even Jasmine snuck a curious glance at her mother.

"Shortly after college, your father and I were researching all sorts of legends following ghost culture. One day we came upon an article about an old river in the woods surrounding Amity Park. It was also the reason we first came here."

Jazz who had set her book down, slowly inched next to her brother. Now, this was a story she hadn't heard before.

"So what about that river?"

Maddie smiled. "It was said to lead to an ancient cave by the name of Antra Elementorum, housing the spirits of earth, water, fire and air. Of course, we wanted to know more. So your father and I travelled here. We searched for several weeks and while we found the river, it didn't lead us to the cave."

"How come we never heard of this legend before? Why is nobody here talking about it?", asked Jazz again. "I mean they live here, don't they?" Trust her smart daughter to question this kind of thing.

"Not much is known about that cave. The old records in the town library have little to no information about it. Most think, it doesn't even exist, as no one has ever found it. The only concrete clue we found is a stone tablet we stumbled upon in the woods. A song, which is connected to the legend, was inscribed on it."

"Do you know it?!"

Maddie laughed, not expecting the twin exclamations.

"Do you want to hear it?" They nodded eagerly.

"Alright, scooch over you two." She leaned her back against the pillows, her children on either side of her. "I believe it went like this..."

"Where the lost ones trace their past,
There's a river and a shadow cast.
Sleep, my darling, safe and sound
For in this river, all is found.

In her waters, deep and true,
Lay the answers and a path for you.
Dive down deep into her sound,
But not too far or you'll be drowned.

Yes, she will sing to those who'll hear
And in her song, all power flows.
But can you brave what you most fear?
Can you face what the river knows?

Where the lost ones trace their past,
There's a river and a shadow cast.
Come, my darling, homeward bound,
When all is lost, then all is found."

- 10 years later -

"What are you humming?"

Danny, who had been appraising his sandwich absentmindedly, lifted his head to meet the gaze of his two best friends. He blushed in embarrassment.

"Huh? Sorry, I wasn't listening."

Sam raised an eyebrow and sighed. "We noticed. Obviously, your sandwich is much more interesting than us. I asked what you were humming."

"... I was humming?"

While his answer had Tucker snickering silently, Sam just muttered something that sounded suspiciously like "Clockwork help me.", before giving Danny a stern glare.

"What's going on with you? You've been off the whole day."

Tucker, who by now had regained his bearings nodded in agreement.

"She's right, dude. You're really weirding us out."

The raven-haired teen took in their expectant faces. "It's nothing guys. I just didn't get enough sleep, that's all. Skulker put up a damn good fight last night." It wasn't a lie. Fighting ghosts kept him up most nights. This time though, it was something else distracting him, rather than the lack of sleep.

The half-ghost had been hearing a strange voice calling for him since waking up this morning. No one else seemed aware of it, which freaked him out at first. Now he just caught himself questioning what it was.
It came and went, never staying long enough for him to find its source. The teen suspected it was a ghost, but didn't want to make a fuss about something that could very well just be a figment of his imagination.

He just hoped his friends would buy his explanation for now.
But judging by their expressions, his chances weren't good.

Luckily, before they could question him more on the topic, the bell rang, signalling the end of their lunch period.

Sam pointed accusingly at him.

"This conversation is not over, ghost boy. Now, come on or we'll be late again."

Danny sighed in relief, gathering up his stuff. While making a grab for his backpack, his body froze. A chill run down his spine.
There it had been again, the same voice.
He made to look around, but a tap on his shoulder stopped him. Tucker was standing behind him, a concerned frown on his face. Sam was not too far off waiting for them.

"You okay?"

"Yeah, it's nothing. Let's go."
He ignored the second call of the voice following him out of the cafeteria. There were more important things for now. Mainly the English test he hadn't studied for at all.
Mr Lancer would kill him. He was so screwed.

Well, I hope you liked it. The meaning of Antra Elementorum will be revealed in a later chapter. Speaking of chapters...
I won't make an upload schedule for this since I hate giving promises I won't keep. I'll try my best to update as soon as I can, but my laziness will probably hinder me in this. You have been warned.
Have a nice day ^.^/