"OK, Sans...now tell us what's wrong with you today?" Toriel's voice becomes serious.

Of course, everyone noticed Sans action, they just didn't want to point out in front of their new friend.

"Yeah! Punk! It's not cool! I have never seen you be so rude to a person we first meet." Undyne kept herself didn't point it out loud very hard! That's why she was so silent.

"Y-yeah...you didn't act like yourself...d-did anything wrong?" Alphys sound worry.

"ARE YOU DON'T FEEL WELL, BROTHER?" Papyrus frown with worry.

"...What's wrong with me? What's wrong with them!! Can't you guys smell that!? They cover in the scent of mating! What are they thinking!? Try to fascinate everyone they meet!!??" He doesn't know why he will be so angry, even (Y/N) want to have sex with everyone they meet that's not his business. But he can't help himself! The thought of that (H/C) hair and (E/C) eyes person be with someone makes him growl. How can they go out like that? He wants to lock them in the room or wash that scent down!

"HA! The smell?? That's the reason you act so weird?" Undyne laughs at him, this reason is ridiculous.

"SANS...WHAT IS MATING SCENT SUPPOSED TO MEAN?" Papyrus unsurely asks. He knows the mate mean your love one, but mating scent? Is that the smell like spaghetti which let everyone love it? Sans did say the scent can fascinate others...

"Ummm......I explain to you later, bro." Nah...he won't explain to him, Papyrus will forget about it soon.

"It's rude to talk about someone smell, Sans. And they smell fine like every human only has their own flavor, I didn't smell the mating scent like you said." Toriel doesn't take that, that's not the reason to be rude to a kind person.

"Y-yeah what are you talking...O-oh my!" Alphys also frown by the reason Sans said, but suddenly, the knowledge about the monsters and humans bump in her head.

"What's wrong Alphys?" Undyne looks at her girlfriend.

"I-I think I know what Sans talking about! OH MY GOSH! OH MY GOSH! I NEVER THOUGHT I WILL SEE IT IN MY LIFE!!!" Alphys is very excited like she finds a new ship in anime.

"Calm down Alphys, do you mind explain to us?" Toriel said.

"W-well...i-it's a private thing...I think I better explain it to Sans only." She almost speaks out without thinking but she doesn't think Sans will like something like it be spoke out in front of people so she stopped.

"Alright, it's only you and me now. Why didn't you guys smell their scent? It's fucking obviously!! Like they soak themselves in it!!" Everyone left to give them space to talk. Sans still feels angry, his friends and family don't trust him was make it worse.

"F-for simple...y-you two are soulmate." Alphys hesitated how to explain and decide to make it simple.

"...................what?" He is lost for words when he heard the new information.

"M-Monsters are more animalistic than humans so when monster mating season the scent also the way to find a mate. B-but the soul mate is kinda different, the soul mate can smell the scent only each other can smell." Alphys explained it calmly.

"T-they are my soul mate?" Soulmate...it was something almost like a fairytale. Sure...some monsters have their soulmate but it's really rare.

"I-I think so, but you still have to check to let your souls meet."

"I-I have a soul mate? For real?" He has a soulmate? A human soulmate? That's why he didn't interesting in any monster before?

Suddenly, he realized something, he didn't be very......friendly at their first meet.

"......Fuck! I stared at them! They probability hate me now!! W-wait! They won't hate me, r-right? Since we are soul mate?" He got panic. A soulmate! How rare it is!! He just out of that damn RESET and now he messed up something so important by herself.

"Ummm......soul mate can decide they want to mate or not, if they choice not......you won't be soulmate anymore and you can't find another one in your life......b-but don't worry! I-It doesn't become that bad yet!" Alphys tried to cheer Sans up but it didn't sound any convincing to Sans.

"Fuck fuck fuck fuck!!! I messed up so badly!! What if they don't want me!? What if they feel disgusting to have a monster mate!? I messed up! I messed up! OH MY GOD WHAT DO I DO!?" He didn't think he will have a mate not to mention it is a soulmate...if he loses them...he can't even get them back!!

"S-Sans! SANS! CALM DOWN!" Alphys yelled and Sans to wake him from his thought.

"HOW CAN I CALM DOWN!!" Sans yelled back. Calm down!? Calm down!? How can he calm down for losing his soulmate just because of his stupid action!!

"They will come to the party tonight you can make it up!" Alphys reminded Sans the party tonight.

"Y-yeah I still have chances! I can make it up......yeah it won't become that bad..." He can't help but think about the worst possible but still try to hope the good.

"You calm down now?"

"Y-yeah...thanks, Alphys...I have to be alone for a moment......" Sans teleported back to his house.

"Shit...what should I do?" He was laying on his bed and sigh.