Chapter Text
"Dipper, look! A ship!" Mabel exclaimed excitedly, latching onto her brother's arm and pointing - to use the term loosely - at the vessel, arm flailing animatedly in its general direction. Dipper jumped slightly at her loud[er than usual] tone in surprise. He quickly looked to where she was pointing.
A large ship was headed their way. Dipper couldn't quite tell whether it was a pirate ship or perhaps the private ship of some sort of business tycoon, as it was completely painted light blue but was well equipped in the weapon's department from what he could see. Granted, he wasn't exactly an expert on humans, nor was he in the perfect viewing position, being under water. Mabel seemed to think the same, as she grabbed Dipper by the wrist and pulled him behind a large, half-submerged boulder, which she attempted to sneakily peer over at the boat.
"Mabel!" Dipper shout-whispered after a short coughing fit where his gills and other breathing orifices couldn't seem to decide which was supposed to be in charge at the moment. "What are you doing?!" He tried to get her to duck behind the boulder. "Get down here!"
"Aw, come on, bro-bro! It's a big, fancy blue ship!" Mabel pouted, whispering as well.
"Yeah, a big fancy blue ship full of humans, and we're up here alone! We don't have nearly enough power to hypnotize the crew of a boat that size! They could kill us!" The boy argued, gesturing wildly as he spoke.
The girl simply rolled her eyes. "Oh, hush. It's not like I'm planning on letting them see me!"
Dipper huffed, folding his arms and frowning. "We still shouldn't be here."
"Relax, Dipdop!" Mabel whispered cheerfully. "We won't get caught!" With that, the female siren silently dove back into the water and swam away.
Dipper followed. To his dismay, his sister seemed to be headed directly toward the ship. "Mabel!"
Her pink scales shimmered with a yellow sheen as the noon light reflected and refracted through the sea water. She sped up a bit as Dipper called out, rocketing under the boat. She looked at its underside, eyes wide in wonder as she reached out and gently ran the tips of her fingers over the wood. She glanced back at her brother, grinning widely, almost taunting.
Dipper stopped before reaching the ship, wary of getting closer. He half-hid in a patch of seaweed and scowled sternly at his sister. "Mabel, get away from there! If the Stans knew you what you were doing, they'd have our heads!"
"Which is why they won't find out what I'm doing. Right, Dippy?" She returned, smiling dangerously at him and giggling when he began to grumble. She turned back to the boat, swimming around its underside, observing it with blatant wonder. "Y'know, boat kind of sounds like butt." She mused. Grinning mischievously, she added, "Hey, Dipper! Guess what?"
"What?" He sighed, complying tiredly.
"I touched the butt." She snickered, laughing even harder at her brother's exasperated groan. Then something flashed out of the corner of her eye, catching her attention. Her head swiveled in its direction, soon followed by her body as she noticed a small box on the sea floor. She tilted her head, intrigued, and went over to it. The box was wooden, about a foot long on each side, and had a few simple designs on it. It had a silver plate with something etched into it on its lid. On the front was what seemed to be a gold, oddly-shaped plaque with some kind of metal rod of the same material sticking out of it. "Dipper, look at this!" She poked the box, and when nothing happened, she lifted its lid. Inside was a small figurine of a female human in a weird pose. Mabel hummed curiously.
He swam forward a bit hesitantly, glancing up at the ship nervously. "Whatever it is, you should probably leave it alone. They might come looking for it, or it could be a trap." He stopped a few feet behind her, refusing to get any closer.
"Don't be so paranoid!" She curiously pulled at the rod sticking out of it, jumping slightly when it easily slipped out. Turning it over in her hands, she realized that it was a key. Mabel slipped it back into the front of the box and turned it.
"Stop being such a mermaid!" He snapped, irritated. Looking at the box from where he was, he got the feeling that something was off. The box was wooden, but it wasn't bloated, so it couldn't have been under water long. That meant that it had either fallen off of the boat above them, or someone had thrown it overboard. Or...
Wait.
The box was wooden.
Wood floated.
Yet the box was sitting on the ocean floor.
What could be inside it that was so heavy, it kept the box from floating?
Mabel blinked in surprise when music started playing and the figurine began to spin. The tinkling melody was muffled by the water, but the tiny human was not effected. It spun slowly and practically mesmerized the siren.
Her brother's eyes widened at the sound of the music. "Mabel... What did you-" Dipper was cut off as something attached to a rope shot upwards, followed by four more notes of the tune, finishing it. "Mabel! Get away from there!"
Mabel gasped when the figurine shot toward the sky, dragging a rope along with it. She stared at it, frozen in shock. Suddenly, a thick net popped out of the box, landing on Mabel. She panicked, flailing and thrashing in a blind attempt to free herself but only succeeded in tangling herself further. Distressed screeches slipped past her lips as she twisted and turned frantically.
"Mabel!" Dipper shouted, though he was too horrified to move. As soon as he realized she was being lifted, though, he rushed forward. "Mabel! Stop moving!" His hands hovered near the ropes, hesitant and unsure. She was quickly being pulled toward the surface, but he wasn't sure what to do. Mabel continued to thrash, and the net continued to be pulled higher, and Dipper was panicking, so he did the first thing that came to mind, which was to grab the netting and pull. Down.
His efforts managed to slow the net for a minute before it resumed its ascent.
"Dipper." Mabel said, voice sad and defeated. "Dipper, you have to let go. They'll catch you too, if you don't."
"I don't care! I won't let them take you, Mabel!" He replied, still trying to pull the net down.
"Dipper," she gently put her hand on his shoulder. "Let go."
Dipper looked up at her, face contorted in anguish. They held each other's gazes in a silent argument. After a moment, expression pained, Dipper let go and watched as his sister was lifted up. Away from him. "I'll get you back!" He cried desperately. "I'll save you!"
Mabel smiled sadly. "I know you will. Good luck, bro-bro."
With that, she was lifted completely out of the water and out of earshot.
Dipper stayed still for a while, gazing brokenly at the spot he had last seen her. Taking a deep breath, he swam to where the two had hidden before and attempted to think clearly. He needed a plan.
He should probably go to the Stans about this. Probably. Most likely. Okay, there was obviously no way he was going to be able to get Mabel back on his own. But who knew where their elders were at this time of day? Ford usually went exploring, and Stan was usually trying to sell stuff. They could be anywhere. Dipper didn't want to risk trying to find them, because the boat might leave before he would be able to. That, and they would probably start yelling at and lecturing him, and there was definitely no time for that. He decided that the most he could do at the moment would just be to follow the boat and wait for an idea or an opening. Maybe leave a note for the Stans, who were bound to come looking for them eventually.
So that's what Dipper did.
Gathering some red and pink coral, the colors of his and Mabel's scales, he put them in an obvious place beside the boulder, and carved the beginnings of a message for them on the side he was hiding on.
Half an hour or so later, the ship began to sail away, and Dipper made sure to add the direction it was going in to the note before following after it.
He would get Mabel back.
No matter what it took, he would get his sister back.