Light in the Dark (Gaster X Reader)

Learning

On your breaks you started sitting with Gaster and Sans. Sans would smile and say something about his break being over and having to go back to work. That left you to talk with Gaster. You enjoyed your conversations with him, especially when he got excited about some science thing or another and started rambling. It was humorous, and kind of cute. "So, Gaster. Tell me about the C.O.R.E." He perked immediately, smiling. "The C.O.R.E apparatus was one of my greatest creations in the Underground, responsible for powering, feeding, and stabilizing the entire civilization! Without it, monsters never would have survived down there."
"I'd have to disagree with you there. Even if you hadn't built the C.O.R.E, I think that monsters would have found a way to survive, somehow." He frowned, contemplating your words before sighing. "Perhaps you're right.."
"The C.O.R.E did change technology in the Underground though." You gave him a win. You were trying to show him that his opinion wasn't the only correct opinion, without bringing him down to much. "I.. suppose it did."

🎭

The conversation went from the C.O.R.E's purpose to Gaster gibberish as he explained how it worked. All you really got out of the rant he was on was that the C.O.R.E took magma and changed it to magical energy to give power, create magical plants and foods, and even small weather patterns like snow and rain. "You look lost." He commented. "Uh.. I think I got it, but if you could try and use smaller words or something?" He laughed. "I can try."
"Gaster?" He hummed. "You said the C.O.R.E was ONE of your greatest creations. What is your greatest?" Gaster hummed again. His phalanges started to thrumb rhythmically on the countertop. "My greatest.." He sounded.. melancholy? Sorrowful? You weren't sure. "My first sentient beings. 1-S and 2-P."
"One- what?" You were confused. "Sans and Papyrus. They were not born, they were created. In my lab. By my hand."
"They.. they were?" You'd had no idea. "They were.. I regret.. a lot of things I've done, and all they things I've thought to do. I've.. hurt them, tortured Sans, abandoned Papyrus.. I've been a terrible father. I always will be."
"Yet.. they are still there for you. You must've done something right then. Maybe you're so busy thinking about all the bad, you've forgotten all the good that happened as well?" Gaster looked at you as if you were a genius. [Y/N].. you may not have a degree, but you may just be the smartest girl in the world." You blushed. "Th-thanks. What's your best memory with them?"
"Well.."

🎭

Sans was 5, Papyrus was not even a few hours old. Gaster was feeding the small skeleton, or trying to. It wasn't taking. "2-P you must eat or you'll dust. I need you alive." He hissed in frustration. "can i try?" Sans asked in a small voice. "If you can magically get him to eat, go ahead." Gaster passed Papyrus to Sans. "1-S! 1-S support the head! Yes, yes, just like that." Sans eyelights glowed blue, Papyrus responded in kind, eyelights glowing orange. They continued to do that as Sans got Papyrus to eat. Gaster would never forget this moment as long as he lived.

🎭

"What happened to change that? Why'd you leave them?" You asked curiously. Gaster seemed rather close to them. "I.. was ending experimentation on Sans. I was going to try and raise them right. Make up for everything, but the C.O.R.E malfunctioned. I.. fell. Got erased from time and space. Sans.. he saved me. From the darkness. From the fear." You were smiling. "He knows. He knows you were done with it all, that you were changing."
"Hehe.. yes. I suppose he did. And I still am."
"Hm?" You gave him a questioning look. "I am aware of what you are doing." He hummed again. "Sans saved me from the dark, but you saved me from the loneliness." You blushed again. "G-gaster.."
"[Y/N]." Crap, Grillby. You faced the bartender. "You're shift started an hour ago."
"Ah! Really?! I gotta go Gaster, sorry!" You dashed to the back. "I'm surprised with you, friend." Gaster tilted his head. "Why?"
"Nothing, nothing. This is good, what you have with [Y/N]." Grillby replied.