Pulling My Heartstrings (Undertale Au Smut)

Nightmare x Reader x Killer

I jolted a little in shock as I felt a slick, wet feeling run up my neck before yelping as I felt the pair of teeth bite down sharply yet gently on the skin. I knew instantly which of the two it was, Killer had always been obsessed with the love-bites. It didn't hurt but I still whimpered in a pathetic way, feeling my heart race a mile a minute,

"K-Killer!~"

I gasped out, feeling myself shiver as his tongue started to trail over the fresh wound, cleaning away the blood that he had drawn. I could hear the faintest of snickers coming from him, the bastard was doing this on purpose, the way I was shaking and how hot and bothered I felt, the way my body was reacting, he was enjoying this.

"Oh darling~?" He purred out next to my ear, "I suggest you be quiet, Nightmare won't be too pleased about us doing it without him~" He whispered, a dark, husky tone lacing his voice as he spoke.

I was going to argue back, to say that he could come back and join us any time, but before I could even try to speak I felt Killer suddenly shove his hands between my legs and force them open, causing me to gasp out and stare. The look on his face was one of pure, unbridled hunger. I was sure if he had eyes they would have been filled with lust.

"Now, now, sweetheart, you've gotta be quiet~" He smirked, a small chuckle rumbling from his throat, his free hand trailing up my inner thigh under my skirt.

"B-But-! Ahh!" I was cut off by a moan escaping my throat, his hands had pushed the fabric of my underwear aside and two of his fingers had slid inside of me. I could hear him snicker once more as I struggled not to moan again. I could feel a blush rise to my cheeks, a small whimper leaving me.

"So cute~" Killer cooed, leaning forwards a little more, "You're just so adorable when you're struggling to keep your moans down~" He purred out, a smirk still on his face. I couldn't even argue back as I could feel his fingers move in and out, slowly at first before he started to pick up the pace, thrusting his fingers in and out quickly. A larger blush appeared on my face as I heard a familiar person clear his throat at the entrance of the room, my eyes immediately locking onto Nightmares. Killer froze before chuckling softly.

"Really, Killer? Couldn't wait for me to get back?" Nightmare chuckled, looking a little annoyed but still had that teasing look on his face, Killer grinned.

"Sorry, couldn't help myself. She looked too good." He shrugged, pulling his fingers out from within me and I whimpered softly. I glanced at Nightmare, seeing him smile a little and shake his head,

"Of course, you're not sorry, I know you," Nightmare hummed, walking over to us, "But I suppose it can't be helped, you are rather needy." He chuckled, standing by the side of the bed, looking at the two of us. Killer grinned as my hands went to hide my embarrassed face,

"Don't say that, boss. You're not much better than me." Killer snorted, a small laugh escaping him.

"I never said I was, I'm not one to lie, now am I?" Nightmare said, smirking a little. He was right, he had always been very honest with us. Killer shrugged and then looked at me, a smirk appearing on his face.

He hummed, his hand moving to start running up my thigh again, my blush getting even deeper as his fingers trailed dangerously close to where I needed them,

"H-Hey-!" I started but was interrupted by a sudden, loud moan as his fingers rubbed against my clit, rubbing it softly, teasingly. I could hear him and Nightmare snickering.

"Look, boss, she's already soaked," Killer smirked, chuckling as his fingers moved back a little, moving around the opening of my hole, "Should we give her what she wants?" He purred, looking up at Nightmare, who was grinning widely.