Error slept on the couch after an argument he had with ink. His snores erupted throughout the house, ink using two pillows to cover the sides of his skull.
    Usually ink would be asleep before error would be but his pelvis felt like it was on fire. It was a cold night and ink was the complete opposite. His whole body felt like it was on fire. He was breathing heavily and weird urges to go wake up error kept bothering him.
    Heat. Ink growled once he realized it. He threw off his covers, swinging his legs over the side of the bed, sitting there, panting like he had just run a marathon. He got up, his feet fighting to keep balance.
    He walks out of the room and grips the railing of the stairs, slowly walking down until he reached the living room.
    Error laid 'comfortably' on the couch. One of his hands laid on the couch arm above his head while his other arm fell off the side. Both his knees were bent, trying to fit themselves between the arm rests.
    Ink stepped over to the couch as he sits on the ground in front of errors face. His heat only got worse. Ink groaned loudly, quick to slap his hand over his mouth. Errors eye lids(?) slowly opened, seeing ink in front of him. He cocks an eye brow as he noticed the rainbow blush on ink's face. "Ink? Are you alright?" error asked in concern. Error noticed ink rubbing his legs together and biting his lip.
    Error let out a sigh and rolled over to face the back of the couch. "Go to sleep ink, i'm not in such a good mood" though error sounded as if he didn't want to, in reality, he was only teasing ink. Ink pouted and shakes error by the torso. Ink turned error over onto his back and started to gently kiss error's neck. Error was trying his best to suppress his smirk, failing. Ink saw this and smiled.
    He started to bite a little harder onto error's neck. His breath hitched and he pushed ink off of him. Ink was surprised, sitting up onto error's abdomen. Error rubbed his neck a bit, a bruise taking color on his dark bones. Error scowled at ink only to smirk soon after. Ink blushed his usual rainbow as error practically pounced onto ink, forcing him to lay on the couch. Ink's hands were forced above his head and tied with the neon blue of error's strings.
    Error dived into ink's neck quickly, biting and nipping at his neck to find a sweet spot. Ink's breath hitched when error bit between ink's shoulder and neck. Ink bit at his lip and tried not to moan. Error continued to tease at ink's neck for a bit, his hands beginning to caress the curves around ink's hip.
    Ink finally gave in and let out a loud moan. Error smiled mischievously, satisfied. Error's hands started to grip around the rim of ink's shirt, pulling and tugging at it until the ecto-body of ink's belly showed. Error started to bite at ink's rib cage, slowly getting rid of ink's clothing. The collar of ink's shirt went over his head flying off into another corner of the room. Ink forced error onto his back quickly, once again, sitting on his abdomen. Ink tugged down on error's shorts, revealing error's ecto body. Ink threw off his own shorts as he lowered himself down onto him, causing error to groan from inks tightness. Ink began to bounce on error as he clutches inks thighs.
    Only minutes after they had hit their climax did they finally lay down. "Still mad at me?~" error teased. Ink huffed and rolled over though it was not very effect from seeing that there was barely any space for him to do so.
    "Y-yes..." ink wasn't really mad but now that error had brought it up he didn't want to admit to it. Error wrapped his arms around ink's waist and snuggled into the crook of his neck.
    "Sure ya are~"...

(I didn't put too much effort into this. My friend in real life requested this, and yes, I had dragged someone from my friend group into the trash bin that is the undertale fandom)

Here ya go: KawaiiLucyHeartfilia