Singing With The Siren [A Fell!Sans x Reader]

Chapter 16

After a week of monitoring and a few check-ups, the sisters were finally going home to the ocean. A party was planned in the caves, everyone they had ever met was invited. The Alphys' and Undynes were already down at the shore setting up. Angelica was shopping with the Mettatons, occasionally texting Y/n photos of dresses she might like. The Sans' and Papyrus' were taking care of catering, along with the Toriels, and desperately trying to keep Blue's cooking separate from everything else. The Napstablooks were sorting out a playlist and the Monster Kids were helping Bf/n with the fireworks for the end of the night. It was going to be amazing, Y/n could feel it.

Meanwhile, her and Edge relaxed back at the lab, both in the large saltwater tank now, Edge's necklace glowing brightly. He'd put on a horror movie, laughing at the jump scares. Y/n, not wanting to be rude, didn't object, but instead had to suffer through jumping four feet in the water every time someone screamed, shivering despite her temperate surroundings. Finally, she just curled up with her eyes closed, screeching as someone pulled her into their lap, thrashing violently in their hold. "Relax, kitten, it's just me." Y/n immediately calmed, burying her head in his jacket, the movie shut off as she closed her eyes.

Edge stared down at Y/n, so vulnerable and cute. He felt kinda bad for putting on that movie, but damn, the payoff was worth the guilt. He'd never been more in love.

Everyone had gotten together to help him ask her on a date at the night's party and my god would he love it if she said yes. Drifting into those fantasies, he slowly drifted off, the siren still huddled against his chest.

A faint buzzing slowly pulled Edge from his slumber as he glared over at Y/n's phone, an alarm buzzing 7pm. Shit. He carefully shook Y/n awake. "Five more minutes..." She yawned.

"Come on, kitten. We're supposed to be at Bf/n's by now, your sister is going to kill me!" Y/n shot upright,

"We gotta go!"

Edge grabbed her by the hand and within an instant, she was sitting in Bf/n's bathtub, already filled. "I was wondering when you two were gonna show up." Bf/n jumped down from where she was sitting on the basin, making a beeline for Y/n. "You, out. The TV remote's on the ottoman."

"Ay, ay, captain." Edge muttered, leaving the bathroom as Bf/n started her attack, teleporting to where he knew Angelica was waiting with his tux, something that matched Y/n's dress to a tee. At least that's what Angel had implied through her mostly dreamy looks, like she was already planning the wedding.

Bf/n was a lot stronger than she looked as she lifted her friend from the tub, dropping her in the canal behind her house, joining her in the water soon after, legs fusing to create a shimmering purple tail that trailed behind her in the blue. Y/n anxiously fixed the black rose perched on her head, trying not to fiddle with the hem of her black and red striped number anymore that she already had. "You look amazing, Y/n. Edge will think so to, I promise. If not, I'll kick his ass." They burst into peals of laughter as they dove under the water, heading for the open ocean.

By the time they arrived, the party was already in full swing, light bouncing off every surface. Purple and gold adored the caves, giving it an almost regal feel, if it weren't for the half drunk monsters strewn along the shoreline. Y/n jumped onto a rock, smoothing out her dress as Bf/n met up with Angelica, both of them going around to introduce themselves.

Edge appeared suddenly next to Y/n, handing her a small paper bowl of her favourite snack. She gave him a grin, scarfing down the treat before Edge lifted the bowl into a trash bag at the borders of the party. As her chewing slowed, she noticed how similar they were in colour scheme, black on red, with just a few gold accents. It was like they were made to be together.

Edge's face began to glow a dusty red, which Y/n assumed was him blushing. It was a good look on him, she had to be honest. "Y/n?" He gently scratched the back of his skull, looking down before regaining his composure just slightly.

"Yea, Edge?"

"I just wanted to tell you, you look gorgeous tonight, doll." Y/n's face matched his now as she resisted the urge to pull the neckline up over her face.

"T-Thanks, Edge. You, uh, don't clean up too bad yourself."

He seemed at war with himself for a moment before shoving his shaking hands into his pockets. "I also wanted to tell you... I, um... fucking..." He sighed heavily, trying to arrange his words in his head. "Look. I love you, ok? I understand if you don't like me back anymore, I won't judge, I-" Now it was Y/n's turn to shush him, pulling him into a kiss.

They pulled away, breathless. Y/n felt her head swim, a warmth beginning to tingle in the tips of her tail, spreading up towards her gills and stopping at her belly. She smiled slightly at Edge's concerned expression, momentarily blacking out as a bright light shone in her eyes.

When she came to, Edge was crying. Before she could panic though, he quietly told her to "Look down, kitten." Then, Y/n was crying too.

Where there should've been a long tail, there were not two significantly stumpier legs. She flexed her toes experimentally, barely daring to believe it was real. She grinned as she pulled her knees up to her chest and straightened them again, enjoying these legs she'd been gifted with. Her gills had also disappeared from below her hip bone, she was breathing actual air!

She threw herself into Edge's hold, whispering her thanks over and over and over again. "I love you, too, Edge."