Sans teleports in front of Papyrus which it jumped him.

"SANS, STOP DOING THAT! YOU KNOW THE GREAT PAPYRUS DOSN'T LIKE SURPRISES!" Sans laughs.

"sorry bro." Sans takes a deep breath before speaking.

"bro...about the human..."

"HM?" Papyrus looks at Sans.

"the human is not a ordinary human I ever seen..." said Sans.

"WAIT ARE YOU TELLING ME THAT THE HUMAN IS-" 

"a mermaid." Papyrus crosses his arms in disbelief.

"SANS, I DON'T BELIEVE YOU." said Papyrus with a stern look.

"papyrus, I'm telling the truth! the human is a mermaid and I'm going to prove it to you!" Sans yelled.

"SANS, MERMAIDS ARE JUST A MYTH THAT MONSTERS TELL EVERY NIGHT OR DAY! THERE'S NO SUCH THING!" Sans groans.

"well, if you don't believe me...I'll take you to her..." Sans grabs onto Papyrus' hand.

"SANS WHAT ARE Y-" Sans teleports Papyrus to Sonja which she curled up in Sans' jacket and more white fish scales are formed in her skin.

"SANS, THAT'S JUST A HUMAN." Sans groans again as he lifts up Sonja's arm, showing Papyrus the white scales on her skin. Papyrus grabs onto Sonja's arm, feeling it.

"SANS...THOSE ARE..."

"yep, those are real fish scales, Pap." Papyrus' eyes sparkled in delight.

"WOWIE! I GUESS YOU ARE RIGHT...SHE IS A MERMAID." 

"Not entirely." Sonja told.

"WE SHOULD BRING HER TO OUR HOUSE WHERE SHE'LL BE SAFE AND REST UP SO SHE'LL GET GOING AGAIN!" Papyrus shouted in excitement. 

"what do you say, kid? are you willing to stay with us for a while?" Sonja nodded her head before coughing. Papyrus picks up Sonja and carries her to Snowdin. The dogs peeked out from the bushes and gasped from what they are seeing.

"Is that human a...fish?" asked Lesser Dog.

"Mermaid." Dogamy corrected him.

"We should keep a eye on her just in case if anything happens to the poor hu-I mean Mermaid." The Snowdin Sentry guards nodded in agreement.

(Here's Chapter 6. I hope you like it and I don't own anything.)