This Is For You, Langga. (18-day Undertale Prompt Book)

"Secret" #1 Prompt

"Secret"
1st Prompt

She was light. So very, very light. It struck fear in his heart. Real fear. It felt like she was slowly dissolving away; into powder, into gas, he didn't know. Either way, he couldn't stop it.

"Sans..." Came her feeble voice. She was weak, and was riding on the monster's back. "Sans, what did you think of... Alphys' true lab...?"

The stout skeleton turned his head back to look at the human. Her entire left face was littered with yellow flowers, big and small alike. What was left of her right one wasn't much, but at least she still had one eye to meet his own red pupil.

"Hnrgh... I don't know, kid... she had some sick experiments, I can tell you that." grumbling slightly, the skeleton hoisted her up more. They were slowly heading to Asgore's throne room. Sans thought he was the only one who wasn't scared to face him. Flowey was oddly silent, and Frisk's hands kept twitching.

A small silence filled the air before Frisk speaks again, softly, "Sans... was it... right... for Alphy's to keep her secret...?"

Sans stopped his tracks and sighed, not in frustration, but in a vague sense of knowing. "Sweetheart, what's this about?"

Frisk kept his words in and slowly leaned her forehead on his shoulder instead.

"Did it bother you? The distorted monsters, I mean."

The short-haired human shook her head. "That's... not it..."

Sans felt like this talk needed time, so ever so gently, he slid Frisk down on the ground and ruffled her messy hair, but was careful not to accidentally brush off the stray flowers growing near the crown of her head. He gave her a patient smile as she looked down and fiddled with her sleeve.

"Ya know... Alphys had every right to keep her secret... after all, her experiments were trials and errors, and the relatives of her experiments knew the risk they were gettin' into." Sans took her trembling hand and placed it near his bony chest. There was no beat there, but as if she knew it was to reassure, Frisk's hand slowly stilled. "But... it's also... bad, if you may, to keep secrets from her friends, especially Undyne. She's hurt about it, I know I would be."

"But what if... it's for the greater good-"

"Sweetheart, if you keep secrets from me, I'd be pissed and hurt... mostly pissed." he tilted her chin up to meet his eyes again. "Even if you experimented on monsters, or heck, killed a monster even, I'd wanna know the important stuff. That's why I trust you, Frisk. You're really an open book to your friends... to us."

Sans gave his signature smile, a golden tooth shining. Frisk smiled back faintly and nodded.

"Then, Sans... Tell me a secret?"

The red-pupiled skeleton blinked. "W-wha?"

"A secret, Sans... I know you have lots... Just one..."

Frisk patiently waited for his confession but was faced by the skeleton's back after a few moments instead. "We should get going, kid."

Frisk frowned sadly and gave a sound of agreement before climbing his back again. "Will you ever tell me...?" She whispered.

Sans was silent after a few steps, but was able to reply shortly, "No, sweetheart, not this time."

And he added, so softly, that she almost missed it. "I can't beg you to stay."