Brother!Eridan x Sister!Reader - Buried Deep

Eridan laid out on his beach towel, letting out a long sigh of relief. He had been pestered by you all day long, and he was just about tired of it. Of course, siblings were supposed to pick and poke at each other, but this was all too much. Now, he could relax, and you could drown in the ocean for all he cared.

“Eridan,” You whispered, poking his bare stomach, “aren’t you going to come swim with me?”

“I brought you here to get away from you,” Eridan grumbled, “I am not certainly not going swimmin’ with you.” He raised his hand and ordered you away with a shooing motion. You frowned and headed towards the water’s edge, half-tempted to kick sand in your brother’s face.

Eridan watched you walk off. Babysittin’ is such a pain... he thought to himself. He closed his eyes, hoping his thoughts would simply take him away - and they certainly did. Soon enough, he fell into a deep sleep on his royal purple towel.

- - - - -

You loved swimming, but boy, was it boring alone. Eridan usually swam with you and the two of you had some pretty exciting splash fights. Without him, the ocean was just a big pool of nothing. After that though, you decided to swim back to shore and get your brother out there with you. You would pick at him until he said yes, no matter what.

You headed back to the beach towels to see that Eridan was sleeping quite soundly. He was pretty mad at you already, so you didn’t want to wake him up. But what else could you do? All the beach activities were boring unless you had someone to do them with.

Then, an idea popped into your head.

“You should never fall asleep at the beach, Eridan,” You said in a hushed whisper. There was a creepy smile practically etched into your face and you clutched a sandy shover in your right hand, “but you’ll learn, won’t you?”

- - - - -

Eridan slowly opened his eyes, hoping to be engulfed by the afternoon sunlight. He was, although he was almost blinded. As he was about to avert his eyes and roll over, he realized that would not be possible. Why, exactly?

He was buried deep in the sand.

“What the hell am I doin’ under here?!” Eridan burst out, wanting to flail his arms so badly. Who could've done this? Oh, he would beat them to a pulp... that is, if he ever escaped the terrible situation.

You peeked out from behind your beach bag, a devious grin on your face. “Oh, Eridan! Bubby, are you okay?”

Eridan glared at you. “Dammit [Name], you’d better get me out of here right this minute so I can strangle you!”

“I’m not letting you out anytime soon,” You replied, “unless you play with me.”

He simply shook his head, not wanting to negotiate with you in any way, shape, or form. “I’m not playin’ with you, I said that already.”

“Okay, fine, but you’ll regret it.”

And with that, you shoveled a large mound of sand over Eridan’s face.

- - - - -

Extended Ending:

Eridan had wriggled his head for hours, but he had finally done it! His face was finally free! As he cried out in triumph, he looked down at his sand-covered body to see that he was now a mermaid.

“[Name], I’ll kill you when I get outta this!”