Frisk’s face lit up immediately, positively beaming.

“S-Sans!?”

…

No response. Confused, Frisk leaned forward and raised her arm to tap her knuckles on the door again.

TAP TAP

“...Sans…?”

Frisk spoke a little quieter, her heart sinking a bit. That was Sans…wasn’t it? 

After the conversion she just had with her mother, it felt like a pit was forming at the base of her stomach. The longer there wasn’t a reply, the more anxious she was starting to feel and she wasn’t sure if she should say anything else at this point. The seconds of silence seemed to be moving at a crawl as she wondered if she should run back upstairs to the safety of her room - until…

“Gotcha.”

A muffled but familiar (and rather smug sounding) voice came from the other side of the door and Frisk felt her anxieties melt away like the sweat that was beginning to form on her forehead. Relief quickly turned to anger.

“Sans! What the heck!”

Frisk shouted at the door - or rather, at Sans, who was on the other side of the door.

“Oh my god I thought you might’ve been someone else! I was freaking out!”

A muffled loud snort and laughter immediately followed from beyond the door.

“Ahahaha! Yeah, I totally got you!”

Frisk let out an agitated huff.

“Not. Funny. Sans!”

Her heart still felt like it was trying to regain its composure. She genuinely almost had a panic attack.

Sans quieted down, but Frisk could tell he was still definitely smiling on the other side of that dumb door.

“Heh, easy, easy. Alright I’m soooorry."

Such a fake apology.

“Man…I know you don’t want anyone finding out about you, but I didn’t think you’d freak out that bad.”

The sound of movement and crunching snow could be heard on the other side of the door as Sans was likely sitting down and making himself comfortable, as he usually did whenever he and Frisk had one of their secret meet-ups.

“What…you some kind of super secret important monster or something?”

Sans gasped dramatically.

“Are you some kind of princess? Locked and hidden away from the rest of the world like in a fairy tale? Heheh.”

Frisk couldn’t help but let out a small chuckle at such an absurd assumption to the reasoning behind her situation, but she also felt uneasy. Though Sans was clearly only joking around, she didn’t like the idea of him throwing around guesses. Sure, Sans was her best friend…her only friend…and though she told him pretty much everything, there was still one thing he didn’t know about her - that she was human - and she wanted to keep it that way. Especially after what her mother just told her. Even as a joke, she didn’t want to risk Sans getting too close to the truth. If he found out…would he even want to be her friend anymore? Would he still keep his promise to never tell anyone about her? She wasn’t sure…and she didn’t want to find out.

“Heh…N-No, Sans, I told you…you know how strict my mom is…if…if someone else discovered I was here and tried to get in and…and my mom found out that I came down here to talk to someone…”

She gripped her sweater again as she tried to quickly deflect Sans’ guessing game.

Sans let out another laugh, cutting Frisk off.

“I know, Frisk, I know. I’m only messing with you. To be honest, I doubt anyone would even find this place anyway. It’s pretty deep in the forest, you know? Er - Well, I guess you wouldn’t know, huh. Heh.”

Frisk let out a small sigh of relief, glad that Sans dropped the subject. But she realized something. Not only did she have to worry about the possibility of a stranger coming to the door on Sans’ side…what if her mom happened to come to the door on her side when Sans was there? She shuddered at the thought, but after a moment, she got an idea.

“I know…maybe we could do something that would let each other know that it’s definitely us, you know? Like…a secret password? Only…something that wouldn’t be super obvious to anyone else!”

“Like a secret handshake?” Sans said sarcastically.

“Very funny, Sans.” Frisk rolled her eyes but couldn’t help but laugh a little. She rubbed her chin, deep in thought, then snapped her fingers. “Ah! How about a whistle? Can you whistle?”

“I’m sure I can get attuned to it.” Sans chuckled.

Frisk snorted at the terrible pun.

“Alright how about…”

Frisk whistled a short tune - one that could almost be mistaken for birdsong if heard briefly by a stranger, but easily recognizable by someone who knew what it was. There was a short pause before Sans whistled the same tune in return.

Frisk clapped her hands together and giggled gleefully.

“Perfect! That’ll be our secret whistle! Now we don’t have to knock anymore and we’ll know for sure that it’s each other!”

She felt immense relief knowing that the chance of a stranger discovering her behind the door or her mother catching Sans has been mitigated drastically now.

Sans chuckled.

“Sounds like a plan, princess.”

Frisk jumped slightly at the absurd nickname and jerked her head around to glare at the door.

“Sans!”

Sans laughed.
“Only teasingggg. 

A soft thunk from the sound of Sans leaning against the door could be heard. Again, something he often did.

“To tell you the truth I’m glad that I’m wrong on that front. I don’t think I could handle having to deal with any more “royal” business right now.”

Frisk also leaned against the door, making herself comfortable.

“Your brother? Or your dad?”

“Both, really. But my bro has been unbearable lately.

Sans let out a sigh and if Frisk could see him, she imagined he was probably rolling his eyes.

“He’s getting ready to take his Royal Guard assessment soon. Well…by “soon” I mean in a year…but he’s acting like he’s taking it next week. He won’t shut up about the damn thing. He’s training non-stop and dragging me into his sparring sessions. He’s relentless.”

Frisk giggled quietly at the thought of Sans sparring with his brother. She couldn’t imagine it…Sans? Fighting? No way.

“And how does that usually go?”

Sans chuckled.

“Heh. Well, I let him win. The sooner he “beats” me the sooner I can go back to enjoying my nap. The Royal Guard is so overrated anyway…I keep telling him…what’s he gonna do if a human shows up? Kill it? I’d like to say I couldn’t imagine him actually going through with something like that but…well…Undyne has been training him well.”

Frisk gripped her sweater nervously again. This was an awkward topic for her considering she was a human and Sans had no idea. She always had to try to play it cool.

“You think…he would do it? Kill a human…?”

Sans sighed.

“If you asked me that a year or two ago, I’d probably say no.”

There was a brief pause.

“Now, though…probably. Though I know in his heart he doesn’t like the idea of it…he looks up to Undyne…and the King…and the Royal Guard…he would probably put his “duties” before his own personal feelings. I dunno. Like I said. It’s so overrated.”

Frisk swallowed nervously. She thought if any time would be a good time to ask…to get any kind of idea…maybe now would be it.

“What about…you?”

A small gap of silence. Probably confused silence. Then Sans finally spoke.

“...What about me?”

Frisk bit her lip. Well…no going back now.

“...Would you kill a human?”

Another pause. A longer one this time. Frisk’s heart started to pick up pace. Had she messed up? Said too much? Sans was smart, she knew that. Could her asking that make him start guessing things again? She could feel the beads of sweat start to form on her forehead again until finally…

Sans let out a dramatically heavy sigh.

“Nahhh I dunno that sounds like a lot of work. I’d rather leave it to the professionals.”
He said “professionals” with a heavy sarcastic tone, then let out a chuckle.

“What about you, then? Could you kill a human?”
He was clearly holding back laughter with that question. He already knew that Frisk definitely would never be capable of killing so much as a house fly.

Again, relief washed over Frisk as she quietly took a deep breath to try and calm her pounding heart. She really has to stop freaking out like this so much. She quickly let out a small chuckle and responded to Sans’ question before her silence seemed too suspicious.

“I think you already know the answer to that, Sans.”

Sans laughed, confirming Frisk’s assumption that he did indeed already know. 

As the barren and empty halls of the Ruins echoed with their continuing conversation, Frisk would feel much more relaxed in knowing Sans didn’t seem to catch on to anything - yet. Try as she might to keep the fact that she was human a secret from her best and only friend, fearing that she would lose him if discovered - eventually that secret, as well as her entire world as she knows it, would come shattering around her.