W. D. Gaster x Reader

UnderSenpai: An Actual OneShot This Time

(Finally did a chapter about UnderSenpai)

I wish I never even fell.

Falling was the worst thing I ever did.

When I fell, I landed in a world where humans were like dragons. Mythical beings that no one knew much about. So when monsters realized there was a human in their presence, I began an instant celebrity. People wanted to be my friend, friend me on UnderNet, and know what I'm up to. I even became a recurring guest on Mettaton's late night talk show. I swear the Underground will never run out of questions to ask me.

People had blogs dedicated to me, fan accounts on the UnderNet, literally every monster is my friend on UnderNet. Thankfully I also have real life to turn to for friends, like Napstablook. He's made so many mixtapes about me, it's sweet. And Mettaton made a clothing line in my honor, and gave me a free room at his hotel and discount on the food. Papyrus and Undyne have come up with new spaghetti recipes for me, and have offered to be my personal body guards. But I declined. Toriel always sends me pies, Asgore sends me tea leaves, and Alphys teaches me about all kinds of stuff about monsters. Like their different biologies and how magic works. And sans is always taking me out to eat.

But, the thing is, I know they're all obsessed with me. Even if they are my friends, they see me as a celebrity. The only person who treats me normally is Gaster. He's my closest friend. I often go to talk to him or just watch him work whenever I'm tired of the attention, which is usually every few days.

He doesn't mind me, he just works casually, as if I'm not even there.

We usually talk. He tells me about what he's doing, and I complain about the attention. But today, I had a different question. "How come everyone is obsessed with me, beside you? I mean, I'm defiantly not complaining that you aren't obsessed with me, but why is that?" He thought for a moment. "Well, I'm one of the oldest monsters here. I've seen humans before. Me and Asgore, we were there during the original war against humans. I doubt he remembers what humans looked like, that's why he took a liking to you. But I, I remember." I furrowed my eyebrows, "How long has it been since you've seen a human?" He shrugged, "Maybe 100,000 years ago. That's when the war ended."

My eyes widened, "That was so long ago! We literally looked like weird hairless apes and we were so ugly." Gaster chuckled, "Yes, you look much more beautiful than your ancestors." I blushed some, "Oh. Thank you." I smiled and he looked back at me, smiling back when he noticed my blush. "I'll admit, you're extremely interesting to me. But, I'm not obsessed because I've theorized on how humans would evolve in my spare time. Though, you are much more beautiful than even my most attractive possibilities." Is he, flirting with me. "Are you flirting with me?" I really can't believe I grew the balls to ask that.

"Perhaps." He said and he then handed me my bottle of water. I thanked him and drank.

I still debate on whether or not that was the biggest mistake I ever made.

Because only a few seconds later, I fell unconscious.

I woke up to giggling, or perhaps chuckling. It sounded deep and familiar. Not deep like sans, but deeper and manlier. Gaster.

I opened my eyes and found myself in a dimly lit room, with Gaster. The only thing is, my left ankle was chained to the floor. The chain was long enough for me to walk a few feet, but I didn't try to. I just looked up at him from where I was sat, propped up against the wall.

"Gaster?" I asked softly, he looked over at me and smiled. "Hello my love." He is obsessed with me. Perhaps even more so than everyone else. "Why are you doing this?" "Because! I. Want. You. It's simple!" "I thought you were my friend." He stopped smiling. "Friend?" He growled, "Never call me that again. I think a term of endearment or simply my name will suffice." "Then what do you think you are to me?" "A lover is what I would like to be." I sighed and closed my eyes a moment. "So, you did all this because you want to be my boyfriend?"

He nodded proudly, approaching me, he seemed very happy with himself. "I just had to have you."

I stood up, looking up at him innocently.

And then I went off on his ass.

"ARE YOU FUCKING SERIOUS?! THAT'S why you kidnap me?! OHHH MY GOD! OOOH! OKAY BITCH! You fucking saw me, always opening up to you, always hanging around you, always watching you, always smiling at you, I even blushed even you complemented me, I DIDN'T EVEN PROTEST WHEN YOU FLIRTED WITH ME! I MADE IT OBVIOUS THAT I LIKED IT! And yet you STILL think kidnapping me is how to make me your girlfriend over just ASKING ME?! REALLY?! When it was EXTREMELY OBVIOUS that I already liked you! No, okay, just. NO! I will NOT be your girlfriend until you let me go, get me out of here, and ask me, LIKE A NORMAL FUCKING PERSON! Then maybe, MAYBE, I'll say yes."

He just stared at me a moment, seeming more scared of me, than I should be of him. He froze for a moment before hesitantly approaching, unchaining me, and leading me out of the basement of the laboratory. Once we were back up there, I slapped him. "That's for kidnapping me!" He looked at the ground, seeming ashamed of himself. "Kidnapping." I scoffed, "That's really no way to treat the woman you care about. You're lucky I didn't beat the shit out of your for it." "Sorry." He mumbled.

I sighed, "Well. Aren't you going to ask me?"

This seemed to lift his spirits, "(Y/N), will you be my girlfriend?" I smiled,

"No."

"What?! But you said-" I cut him off, "Maybe is what the fuck I said." He sighed, "How can I trust someone who literally kidnapped me! No, you owe me, big time." He looked at me, still deflated, but curious, and with a glimmer of hope still in his eyes. "What do you mean?" "I mean, if you want me to be your girlfriend after you did THAT, you gotta make it up to me. Then, ask me again, and I'll say yes." He reanimated before my eyes, smiling down at me, "Really?! You mean it?!" I nodded.

"Then take my word for it, I'll do anything to make it up to you! Anything."