Welcome to Monster Falls

I'm a Monster

AN: The song is "Problem" by Becky G. I do not own it. I also don't own any of the fan art. It's almost exam week for me, so I might not be able to update in a while.
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Dipper felt tired.

Mabel and him had been swimming for about an hour, both of them trying as hard as they could to escape the beaver creature.

His lower body felt really heavy for some reason, like as if his legs had gained 10 pounds. Weird, Dipper thought. Mabel seemed to be having no problem swimming, in fact, she seemed to be cutting through the water like a fish.

Just when he thought that he would sink because his arms and legs were numb from exhaustion, the dock of Gravity Falls Lake came into view.

"Dipper! It's the dock!" Mabel yelled, seeing it too.

"Swim to it!" He yelled back.

With a couple of more strokes, they reached the edge of the water next to the dock. Dipper and Mabel stretched out on the ground, lower bodies still in the water.

"That was interesting," Mabel said, looking forlorn at her drenched sweater. "I liked this sweater," she muttered.

"I have to write this in the Journal-" Dipper started, but then stopped, realizing that he had had the Journal in his vest pocket when they went for a swim. He quickly took the book out, finding it very wet.

"Oh no! No, no, no!" Dipper groaned. He surveied the damage, desperately hoping for the best. Some lines on pages were smudged by the water, although you could still make out what was being said. The leather cover seemed to be okay, dispite it being soggy. Dipper sighed in relief. His Journal sustained minimal damage.

"Calm yourself Dip Dot. We're alright. That curse did nothing!" Mabel said, a bright smile on her face.

"I curse ya! I curse ya and anybody who comes inta contact with ya! Ya think I'm a monster? Just ya wait!" The creature's words rang in Dipper's mind as he remembered, and he wondered what it meant by it.

Mabel's face suddenly slacked, smile becoming a hard line. "Dipper, what's up with your ears?"

"My ears? What's wrong with my ears?" Dipper asked, confused as to why his sister was asking him the strange question. He reached up to touch his ears, and instead of finding soft cartilage, he was met with soaked fur.

What?

He scrambled the rest of the way onto the ground in surprise, his legs feeling much more awkward than usual.

"Dipper! You're a deer!" Mabel gasped.

WHAT?

He looked down, expecting to see his shorts and his noodle legs, but saw neither, his lower body being the body of a deer. "Bahahhhh!" He screamed, his scream being more of a disgruntled deer noise.

Mabel dragged herself out of the water, but was soon gasping like she couldn't breath. Dipper stopped his panicking when he saw his sister struggle. He froze when he saw that she had a fish tail instead of legs, and silently thought that yes, Mabel was right about the river turning people into mermaids.

He pushed her back into the lake, where her breathing returned and she first noticed her new fishy status.

"I'M A MERMAID!" Mabel squealed. She looked at her tail, admiring the pretty pink scales. "I was right! I was right!"

While Mabel seemed relatively happy about the new changes, Dipper was having a mental breakdown. How-? Why-? When-? Gahhhhhh! Asdfghjk! Dipper's thoughts were all over the place, not one coherent. How are we going to tell Grunkle Stan?

"Mabel, how are we going to tell Grunkle Stan?" Dipper asked his twin, who was currently blowing bubbles in the water.

"Can't we just tell him?"

"Are you kidding? He doesn't know about this stuff! He'll have a heart attack or something!" Dipper fretted. "He's old!"

"Yeah, I guess," Mabel agreed. Her eyes brightened, "What if we go find Wendy and Soos? They know about the Gravity Falls weirdness."

Dipper mulled this over for a minute, finding nothing wrong with this idea. "Okay, we'll go find Wendy and Soos."

Dipper slowly started to get up, his deer legs shaking under him. He carefully took a step, knees buckling and face planting gracefully.

"Haha!" Mabel laughed, tears gathering in her eyes.

"Shut up," Dipper grumbled. He was more successful on his second attempt, managing to take a couple of steps. It was strange, moving four legs instead of two.

It's okay, I'm just half deer and Mabel's a mermaid, it's totally and completely NORMAL-Oh who do I think I'm fooling? Dipper thought.

"Um. Hey bro-bro?" Mabel from behind him. She looked unsure.

"What Mabel?" He turned to look at his sister, who was swimming back and forth in the shallow shore.

"I can't really breath out there."

Right, Dipper remembered. "Oh," he said intelligently. "I guess you'll just have to stay here until I get help."

"I wanna go too, but I also don't want to die," Mabel said seriously, her hand under her chin. "Or is it worth it?"

Dipper decided to stop his twin's thought process right there.

"Just stay here. I'll be back with Soos and Wendy," Dipper told her, starting to walk in the general directon of the Mystery Shack.

***

Dipper stayed in the shadows, careful to avoid any townsfolk.

He finally arrived at the old, falling apart building, the last of steady stream of tourists that usually came to the Shack leaving. Dipper knew that Wendy was most likely still at the cashier, Soos most likely was with Stan, which made getting to him harder.

Mabel wouldn't mind if he only told Wendy right?

He blushed at the thought of telling Wendy a secret only he and his sister knew. His stomach was in turmoil as he wondered how Wendy would react to him being half deer. Would she still like be friends with him?

His feet (hoofs?) seemed to be workup autopilot, and before he knew it, he had entered the Shack Gift Shop. Wendy was at the cashier, a bored look on her face. Dipper couldn't help but think that she looked pretty.

"W-wendy?" He stammered.

She turned her head to look at him, half lidded eyes widening. "Dipper?" Wendy said, "Is that you?"

She got up from her chair, rushing over  to where he stood. Dipper prepared for some horribly dramatic rejection or deeply expressed disgust.

"What a cool costume dude!" Wendy cheerfully told him, a large smile on her face.
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