A/N - I'm going to start a series of smut short stories featuring my OC Rose and different AU Sans. I am also taking requests on my tumblr or you can pm on here with a request!

Summary: Sans never knew a relationship was more than just sex. He never factored in Rose's feelings. He quickly learns that maybe a relationship is more than just sex.

(Bara Underfell Sans)

Underfell - Learning How To Love

Sans stood outside Grillby's underneath the awning above the door. It was pouring rain outside like usual in Ebott city and figures it was pouring on his only day off. He worked as a security guard at Medivac Industries, the company the researched human and monster medicine. It was pretty sweet gig. He got paid a pretty penny to just sit around for eight hours and watch his girlfriend work. That's right...Sans happened to work the same shift with his girlfriend, Rosalie. He smirked to himself as he thought of Rose.

Long light brown hair that went down her back. Easy to hold onto when he fucked her from behind. Her slim yet curvy hour glass figure that accentuated her delicious hips. Those perfect tits that always seemed to strain against her blouses she would wear to work. And that ass...Oh that perfect ass...So perky and perfect...Her ass felt so nice in his phalanges. Her buttocks was probably his favourite part about her body.

"shit..." Sans swore as he felt himself grow hot. The things that Rose did to him...Even when she wasn't around, she drove him wild. He quickly finished his cigar and threw the butt into the wet street before heading inside. e sat aHe fjdfjnsdfkjnhdfHe sat at his usual bar stool and finished the bottle of mustard and the glass filled with ice and cheap whiskey.

"yo grillbz' put it on my tab." The skeleton said in his usual gruff voice. The purple flame elemental glared at Sans and shook his head.

"Not tonight Sans. Your tab is due and I won't tolerate it anymore."

Sans rolled his eyelights and pulled out his wallet. He cursed as he saw he had no money in it. That's right he was broke until payday...

"sorry grillbz' broke until tomorrow, looks like yer gonna have ta wait a little longer." Sans smirked at the bartender, his golden tooth shining in the dim lighting of the bar.

"Sans don't even or I'll have the dogs beat the shit out of you."

"come on grillby, 'll pay ya tomorrow i promise-,"

"Come on Sans pay your fucking tab and be on your way." Doggo came over and cracked the knuckles of his paw. Even though Sans was over six feet Doggo was still taller than him. Sans ignored him looking down onto the bar. Suddenly Doggo grabbed his shoulder and forced him up, making the skeleton yell out and push the canine away.

"don'. ev'a. touch. me." Sans warned. The dog was about to punch Sans out when door of the bar chimed and a gasp was heard.

"Wait! Don't hurt him!" A female voice said in a panicked tone. Rose placed herself between Sans and Doggo. Her hands were in front of her in a submissive manner in order to calm the situation. But she felt her magic flare up just in case she needed to summon her shield or her blue magic restraints. From behind her Sans eyed her outfit she was wearing. She was wearing her short black cocktail dress with only one sleeve on the left and grey shawl around her shoulders. That was right...it was their date night and she was supposed to meet him after she had finished her night class.

"How much does he owe you Grillby?" Rose said as she turned towards the bartender.

Grillby relayed how much Sans owed him and Rose paid his tab off, dragging a fuming and embarrassed Sans out of the bar.

"what the fuck! i had it und'a control!" Sans yelled at her. Rose stopped and let go of his arm, turning around to glare at him.

"That was control!? Doggo was ready to punch you out!"

"i can take 'im! ya made me look weak!"

Rose pinched the bridge of her nose with her thumb and index finger.

"I paid your tab. Again."

"whatev'a...see ya at home, dollface."

Suddenly Sans disappeared leaving Rose alone in the rain. Again...The young woman sighed and walked towards the nearest bus station in the rain. She was starting to wonder why she even starting dating Sans in the first place. He was a complete asshole towards her. He didn't give two fucks about her the only thing he seemed to be interested in was the sex. Sure the sex was fantastic but Rose didn't just want sex...She wanted to be able to be respected and loved. Cared for and told she was beautiful every once in a while. She felt tears begin to sting her eyes...Her kindness was starting to make her life miserable...She was too much of a coward to confront her boyfriend face to face, since Sans had a hard time controlling his temper. But what really held her back was the fact she didn't want to hurt him. He was not exactly the most emotionally stable person in the world. And his was feelings hurt easily more than he liked to admit it.

As the bus pulled up to the station, her clothes were completely soaked and she was shivering. She sat in the furthest seat in the back lowering her gaze from everyone who was staring at her. She shivered and let out a almost heart wrenching sob. An old man noticed her shivering and gave her a look of pity. He got up from his seat and sat beside her shrugging off his large coat and placing it around her shoulders. Rose looked at him in surprise but allowed a fake smile to grace her pink lips.

"Thank you." She said between chattering teeth. The old man gave her a concerned look.

"Did someone just leave you out there by yourself, Dear?" He asked her. His voice was gruff and sounded like he was a heavy smoker. Almost like Sans.

"Nothing new there...It's okay I'm used to it by now..." Rose said as she looked down at her lap. The elderly man placed a hand on her knee and patted it gently.

"Whoever it was that left you out in the rain, is an asshole. What kind of man leaves a woman out in the rain!?"

Rose chuckled.

"It's okay. He's got a lot going on right now, like stress and some emotional stuff. I mean I still love him but he just doesn't understand that I'm there for him. I don't think he understands what a relationship truly is about..."

The man chuckled,

"You have a lot of patience. He is lucky to have someone as understanding as you are."

They talked for a while before the bus the pulled up to the stop right in front of Rose's apartment. She attempted to hand the man his jacket back but he refused.

"I have another one. Keep in case he leaves in the rain again. And don't be afraid to talk to him, you are a strong woman and deserve to be treated as such."

Rose thanked him and was pulled into a hug before she got off the bus. She walked up to her townhouse and took in a deep breath before opening the door and walked in. She immediately kicked off her stilettos and walked into the living room. Sans was sitting on the couch in his red turtle neck sweater and black boxer shorts. His one arm propped up on the back of the couch and a can of beer in his other hand. Rose rolled her eyes walked to the coffee table to pick up her makeup bag. Sans immediately grabbed her arm and glared at her.

"who the fuck gave ya that coat!?" He demanded. Rose tried to pry her arm away but he held it tightly.

"Let go!" She yelled.

"i asked ya a fuckin' question!"

Rage filled Rose and ripped her arm from his grip ignoring the sharp pain from his clawed fingers ripping her flesh slightly.

"A true gentleman gave me this coat because I was freezing by being left out in the rain! AGAIN!"

Sans opened his mouth to speak but Rose stopped him. Tears streaming down her already make up stained cheeks.

"I'm getting sick and tired of being treated like garbage! I've been nothing but kind and patient with you and this is the thanks I get!" She placed her face in her hands and sobbed loudly. "I can't believe I left one bad relationship to get into a even worse one..." She said to herself quietly.

Sans felt his soul almost shatter. He hadn't realized just how badly he really treated her. She was always there for him but he was never there for her. He left her by herself in the pouring rain on more than one occasion. He always made excuses why he couldn't go out with her when she wanted to. He wasn't even there for her when her cat died!

"sweetheart...i..." His words fell on deaf ears as Rose quickly walked into their bedroom, slamming the door behind her. Sans sighed and placed his beer on the coffee table and ran his hands down his face. "fuck...i really am a shitty person..." he said to himself. "she's literally the best thing in my life and i treat 'er like garbage..."

He waited about twenty minutes before walking over to their bedroom door. He gently knocked on it but no answer. He turned the knob surprised it wasn't locked. As he opened the door the room was dark except for the small nightstand lamp that illuminated the lump of a person on the bed. Rose was laying on her side towards the wall, under the covers. Sans sighed once again and walked over the bed sitting behind her.

"sweetheart...are ya awake?" he asked her softly. Rose sniffed and nodded, making his soul hurt. "sweetheart 'm sorry. 'm sorry that i treat ya so bad. i can be a bit of a bonehead sometimes." he tried to joke a little bit to make her feel better. His soul flipped in joy as he heard her chuckle slightly. She turned on her back on looked up at him. Her blue and green eyes were puffy and red from crying. Sans gently tucked a strand of her brown hair behind her right ear. He was never this tender with her and it brought a smile on her pink lips. She gently grabbed his hand and kissed his palm.

"Are you okay?" She asked him. Sans red eye lights stared at her in shock but he gave her a soft smile. He cupped her cheek and rubbed his thumb across her cheek. Rose nuzzled her face against his hand.

"'m fine dollface. but i should askin' ya that."

Rose laughed lightly and sat up, looking into Sans eye sockets.

"I'm okay. Like I always am." Rose looked away from him for a second. "Listen I'm sorry if I embarrassed you back at Grillby's I just didn't want to see you get hurt."

Sans eye sockets widened in shock,

"why the hell are ya apologizin'!? i was the one who was bein' an ass. ya have every right ta be mad" Sans looked away and closed his eye sockets, he couldn't even look at her. He didn't deserve to be looked at by those beautiful blue and green eyes.

"I know you're upset at yourself." She said trying to get him to look at her. She pushed herself up into a sitting position and placed a hand on his left cheekbone to make him look at her. His eye sockets opened half way, his red eye lights staring into the deep pools of green and blue that he loved so much.

"I get it you know. All your life you've been treated like shit and garbage. You don't really know what it's like to be in a relationship, right?"

Sans nodded solemnly. Rose gave him a gentle smile,

"That's why I'm still here. I want this work I really do...And I can try to be a bit less pushy..."

Sans chuckled.

"yer not pushy at all baby doll. yer right, i want this ta work too. so i promise 'll be a better 'bonefriend' from now on. and ya know how i feel about making promises."

"Yeah like the promise you made to kill Jerry whenever you seen him again?" Rose said with a playful glint in her eyes. Sans pulled away from her hand and pinched the bridge of his nasal cavity.

"ah man. that guy is such an ass. 'e's lucky i didn't kill 'im fer grabbin' ya ass!"

Rose giggled once again.

"Well my ass is pretty grabable." She said with a smirk, her eyes giving him a dangerous look. Sans looked down at her and gave her a big toothy grin. Showing off his rows of sharp teeth.

"yeah and who does that ass belong ta?"

"You, only you Sans."

"damn straight. ain't no one ev'a touchin' this ass but me." He reached under the blanket and squeezed her hip suggestively. Rose giggled and wiggled her hips slightly making Sans growl possessively. "but 'm as much yers as ya are mine. my soul belongs ta no one but ya, baby doll."

"And my soul is yours. Will you-,"

"no."

"But you said-."

"it's not that i don' want ta see yer soul. stars ya have no idea how much i want ta see yer soul. but i can't. not yet..."

"I understand. I'll wait..." Rose said with a small smile. Sans felt happiness fill his broken soul.

The truth was he was embarrassed to show her his soul. It was cracked and scarred from everything he went through in the underground. He knew she wouldn't judge him for it but he wasn't ready yet.

He leaned in and kissed her soft lips, pressing her back down onto the bed. His hands squeezed her hips again and squeezed them gently earning a soft moan from her. Sans summoned his long red tongue and opened his teeth pressing it to her lips asking for entry. Rose happily obliged and opened her mouth immediately feeling the tongue plunge into her mouth and explore her wet, hot orifice. She moaned louder this time bucking her hips to his pelvis, which was now in between her legs. She felt the huge bulge in his shorts press against her already wet sex through her boy shorts.

"Sans...please touch me. Please fuck me..." She begged him as they parted their mouths. Sans growled and closed his eye sockets regaining control of himself.

"no...i want ta do this right. 'm gonna make love ta ya tonight. not just a fuck. i wanna show ya how much i..." He paused for a moment trying to think of the right thing to say. He watched her expression which remained unchanged. "how much i love ya, babydoll."

Rose gave him a huge smile and pressed a loving kiss to his teeth before pulling herself away.

"I love you too, Bonehead. So please...make love to me. Show me how much you love me."

~~~~oOo~~~~

Rose had no idea how things could escalate so quickly between them. First it started out as sweet tender kisses that turned into passionate kisses. Then a flurry of her clothes coming off and his shirt coming off. Now she was moaning as the skull of her boyfriend was buried between her legs, so deliciously eating her out. Her legs spread apart further and her hand was placed on top of his skull as his tongue wiggled inside of her. His boney thumb circled around her clit at the same speed and furor as his tongue. It ghosted over her sweet spot and she cried out her pleasure, hand clawing at his skull.

"that the spot, baby doll." Sans said in a husky voice.

"Fuck yes!" She moaned out. "Don't stop! I'm so close!"

"mmm cum for me, baby. let me hear ya sing fer me."

Sans tongue hit her sweet spot once more and Rose cried out his name as she came all over his tongue. Sans hungrily lapped up all of her juices that leaked out of her entrance.

"Too sensitive..." She breathed as she slumped onto the bed. Sans chuckled and pulled away from her pussy, tongue licking his teeth. He pressed a kiss to her inner thigh.

"fuck yer so beautiful, baby doll." He said as he trailed kissed up her stomach to her breasts. He gently placed his mouth carefully around her nipple and sucked on it gently.

Rose moaned lightly and gently dragged her nails on the back of his skull, which made him groan against her areola. He loved the feeling of her scratching the back of his skull, it always made him purr. He kissed up to her neck and scraped his teeth across her shoulder over the bite he gave her when they first had sex.

"Bite me...please I need you to mark me again." Rose begged. She was such a fucking masochist...

Sans groaned and sunk his sharp teeth into her shoulder. Rose gasped in pain, her hands gripped his shoulders. She cried out in pain as he grinded his teeth into her flesh, sucking up the blood from her wound. The pain quickly ghosted into pleasure and she grinded her hips against his pelvis, silently begging him to enter her.

Sans retracted his teeth from her shoulder and lapped up her blood with his red tongue. He loved the taste of her, between the juices she produced when she was aroused to her blood which her body desperately needed. He cleaned the blood from his teeth and kissed her cheek as an apology for hurting her. Rose smiled and gently scraped her nails along the back of his skull gently.

"ya ready fer my cock, baby?" He growled in her ear. Rose nodded feverishly, completely dazed with lust. "hang on ta me baby doll. 'm gonna make ya feel so good."

Sans pulled the hem of his shorts down and his huge red cock bobbed out. Precum was already coming out from the head of it. He lazily stroked it and positioned himself at her entrance.

"still so wet..." He moaned out as he rubbed his shaft along her slit. Rose's hips jerked as it brushed her clit. He moved the head of his cock back to her wet hole and he gently pressed it into her. Rose bit her lip as she felt the sweet burn of his head filling her hole. He was going slowly and gently which was unlike him. Usually he slammed into her and pounded into her relentlessly but this time he wanted...no he NEEDED this to be gentle. He needed to show her how much he loved her.

He slowly moved himself further inside of her, pressing his teeth to her lips once more in a loving kiss. Finally he hilted within her, earning a moan from her which he eagerly swallowed. He pulled away from her and looked into her blue and green eyes and saw nothing but love and adoration in them. He smiled at her gently and pressed his forehead to hers.

"I love you." She whispered to him, a small smile appearing on her lips. Sans chuckled and pecked her lips.

"love ya too, baby doll." He gently stroked her cheek with a thumb. "'m gonna start moving."

He pulled out slightly and pushed in, moaning at the feeling of her tight walls pressing against his thick cock. She was always so tight no matter how many he shoved his cock into her pussy. He slowly thrust in and out of her just enjoying the feeling. He felt Rose wrap her legs around his pelvis and move her hips in time with his thrusts. Who would have known that gentle sex felt so good.

"that's it baby, take my cock like a good girl." He said as he buried his face in her neck. He inhaled her sweet scent that made him groan loudly. He whispered soft praises to her as he continued to make love to her. Telling her how good she felt, how beautiful she was, how much he loved her.

His thrusts started to speed up as he got lost in his own pleasure. He could Rose cry out his name and her inner walls tighten around him.

"are ya close baby doll?" he asked as he assaulted her neck with gentle nips and kisses. Rose muttered 'yes' barely able to form coherent words. "cum for me. stars i need ta feel it!"

His cock hit her sweet spot over and over again. Intense pleasure exploded within Rose and she practically screamed his name as she climaxed. Sans growled and began to pound into her, riding out her orgasm. The woman was completely lost in her own pleasure, eyes squeezing shut. She felt another orgasm creeping in her loins.

"Oh fuck! I'm gonna cum again!" She cried out. Her hands gripped his ribcage tightly, white knuckling as she felt another orgasm come on. Her whole body spasmed as she had the most powerful orgasm she ever had in her life. Her mouth bit done on his clavicle to prevent her from screaming out loud.

"FUCK!" Sans roared as he hilted within her, his cock spasming as he spilled his magic seed within her womb. He had never came so hard in his entire life, his soul was pulsing at a dangerous place. His magic was going out of control and his left eye flared red, grinding his teeth to try to control it. After a few more seconds his orgasm finally slowed to a halt, his soul returning to its normal level.

He pulled out of her collapsed beside her panting for breath he didn't need. He felt the bed shift and saw Rose was now laying on her side looking at him with a satisfied grin on her face.

"Hey."

"heya." He chuckled and pulled her closer to him. He sighed contently as Rose nuzzled her face into his massive chest. She pressed soft kissed to the sweaty sternum.

"You smell like sweaty socks..." She mumbled tiredly into his sternum. Sans rolled his red eyelights and was about to retort when he heard her steady breathing indicating that she had already fallen asleep.

"I love you..." She mumbled in her sleep. A soft smile graced Sans rough features and he placed a kiss on the top of her head.

"i love ya too, sweetheart."

A/N: Mmmmm fluffy Underfell Sans. I love it!