An Oath of Mercy || UnderFell Sans x Reader

eleven

The boy waved, relief obvious in his expression, before Papyrus pushed him towards you and Sans. He stumbled and nearly tripped, glancing back at the skeleton with fear before turning his full, excited attention to you. "(Y/N), you have no idea how great it is to see you!"

"Leon, what the hell are you doing here?! And how are you unscathed??" you shouted, thinking you must be hallucinating.

"Who the fuck is he?" Sans looked between you and his brother, torn between anger and confusion.

"I FOUND HIM TALKING TO THAT FLOWER. HE SAID HE KNEW OUR HUMAN." Papyrus was wearing his customary scowl with his arms customarily crossed. He towered over Leon, a fact the boy was well aware of. Leon hustled out of Paps' shadow to get in your personal space, but Sans stepped in the way. His gaze was indignant, bordering on possessive.

"Who the fuck are you?" he demanded. Leon was quick to put his hands up in surrender, still the same shy and easily intimidated boy you'd fallen in love with. But why weren't you overjoyed right now?

"I'm Leon, (Y/N)'s boyfriend," he explained quickly, his words coming out in a squeak. Sans whipped around to stare in befuddlement at you—his anger completely gone.

"Him? Really??"

"What?" you protested, crossing your arms. The other two looked lost at the sudden tone shift.

"He couldn't hurt a damn spider, much less fuckin' kill ya." He rolled his eyelights, his tone mocking the 'he' in question. You'd built Leon up to be a giant, cruel man, yet this wimp in front of him was nothing more than a terrified mouse.

"I'm sorry, what?" Leon spoke up, looking at you in astonishment. "Why would I kill you??"

"Look, I thought you abandoned me down here, I was feeling a little betrayed," you mumbled. It sounded insane to you now—you really were poisoned by the Underground's kill or be killed way of thinking. But you had so many questions for him; your false assumptions could wait until later. "But anyway, what are you doing down here?!" He took your hands in his—much to Sans' displeasure.

"After you fell, I tried to find a way into the hole after you. But, um, there wasn't any way I could save you. So I went to get help, but they called me insane." He huffed, a quiet sound compared to Sans' angry huff. "Apparently the authorities are squashing any rumors about Mount Ebott, and anybody that falls in they label missing and leave it at that. I couldn't even scrounge up a search party! They threw me in a cell for a couple nights to deter me, but..." He pulled you into a bone-crushing hug, and you let out a small gasp of surprise.

"You followed after me?" you whispered, holding his soft face in your hands as his hands moved to hover over your waist. His gaze flickered down to the floor.

"Well, I might've fallen in by accident, but um..." He tried to pull something out of his pocket, but it got stuck and he struggled for a couple seconds. The skeleton brothers looked at each other, sharing a silent 'wtf' look. Then Leon got it out and presented it to you. Your jaw dropped. His skittish behavior made complete sense now! "I was hoping to propose to you that day." He opened the box to show you the ring you'd told him months ago you thought was pretty. Your heart melted at the sweetness and you could barely tear your eyes away from it to look back at him. It was a very pretty ring.

"You are the sweetest fucker in the world," you laughed, pulling him into another tight hug. He startled, looking a little confused but still happy.

"I- You've never called me that." It was an awkward chuckle, and your eyes widened at the realization. Over Leon's shoulder, you met Sans' eyelights, and he looked a tiny bit smug. Not only did you look like a mini him—still wearing his jacket from last night and head to toe edgy red and black—but now you were adopting his dialect. It was probably better Leon couldn't see your flushed face.