Sans soul is growing dimmer than usual, seeing your soul mate be with someone else is bad enough to him....Monsters may not have a heart like human does, but if they had found their soul mate, God know how their will do anything for their half...
Sans is no different from the rest of monsters kind, he would do anything.. everything, for Frisk...and if that's mean he must let her go... then he will let her go...even if that's killing him in process.

Papyrus really want to make his brother feel better, but he know that no matter what he do, there will always a huge crack in his soul that can't be repair with anyone else but Frisk...

Sans never tell about his meeting with Frisk to Frisk brother, Asriel. Sans know, once he knows that his sister is alive, he will get more sad if he know that his own sister is forgot about him and already have another brother...
When the incident happen, Sans and Paps is the one who take care of Asriel like their own brother, and because of that, Sans didn't wish to see Asriel suffer once again... well until he can bring Frisk memory back..

That day, Sans decide to buy a new phone, well he doesn't really need that thing but his bro really worried if he leave him alone and force him to buy another one, his old phone is gone... maybe broke when he fall, he never know.
Sans buy a new one... without a touchscreen of couse because you know.. skeleton problems... he have no skin? how can he use his phone if it's touchscreen... well he tried once with Alphys phone and welp... no luck...

Sans put his new phone in his oversize pocket and walk his way home, but then he get passed by person who punch him straight on his face when they running madly from something...
Sans hp is 0,5 now thanks to them or more like she...there is no way she can get away from him without apologizing and hit Sans when he was in such a bad mood didn't help either..

Sans see her turn to a dark hallway and he smirk, Sans teleport himself to where are she going and face her back... she wear a oversize black jacket and look like holding a bag full of jewelry.... whoa... a thief...
Sans clear his throat, catching her attention and he was success when he notice her body become so tense.

"Is rude to leave someone who you punch in the face without apologize miss... can you give me some.. or you prefer me to teach you how..."

Sans dark and cold voice echoed, but he surprise when she didn't seems afraid... even it's look like she let out a relieved sigh.

"Come on Sans... don't scare me like that"

She turn around showing her large smile to him, His eyes sockets went wide when he saw his own soul mate standing right in front of him...

"F-frisk... what are you doing here?"
"Well duh mr cleaver... I'm stealing of course"
"B-but-"

Sans word get cut when she tackle him to the ground and cover his mouth, she let out a quiet 'Shh..' and then lay on top on him, seems like watching something that dangerously close to them. Sans soul beat faster, he feel familiar warmth from her body... and he miss it... so much.., but one thing that made his hope rise up... her heart, beating fast like him in her chest... his heart remember him... even if she forgot him...

With gentle gesture, Sans remove her hand from his mouth and smirk while whispering quietly..

"Do you want me to get ride of them?"
"You can do it? i mean.. don't hurt them.. just.. make them go away"
"Anything for you, sweetheart"

Her heart beat getting faster...

"D-dont call me that... and yes please do it"
"But... nothing in this world free you know"

She stare at him in disbelief, and Sans chuckle silently at her expression, making his ribcage vibrant, tickling her...

Her heart beat getting faster...

"How could you!?"
"Nah.. take it or leave it?"
"Fine!! what do you want!"
"Kiss me or give me your phone number"

Frisk face exploded with embarrassment but she losing time... they foot steps geting nearer... she nodded and put her face to his chest, refusing to look him in the eyes.

Her heart beats getting faster...

Sans chuckle again but this time he doesn't bother to hide it. With snap of his finger, they are gone..

"Wha- what did you do to them!!?"
"Relax honey... i just teleport them to another place... now can i get my reward?"

Frisk face flush red and hand him her cellphone... welp...no kiss then..
Sans save her number and named it as "My Love" he chuckle happily and preparing himself to go home... then he felt something grab his hands and spun him around.. but what made him froze is a soft lips that touch his teeth...

"Think this as bonus"

Frisk run with blush covering her face, leaving Sans who still standing there in shock... well... heart never lie...

Their heart beat getting faster....