The newest installment in the Bath Time Fun Time series! This time we're tackling Underlust. I was actually debating whether this title would go to Underlust or SwapFell. It ended up being Underlust xP

Though I do have a week off of Uni, I do have a lot of shit to do so I don't know when the next one of these will be out. We're down to two anyways: SwapFell and Gaster!Bros. I might do a bonus Human Skele Bros for myself and afterwards, if no new requests come in, we'll be done with this series.

Quick side note: The universe of Underlust is the creation of nsfwshamecave. They've got a great blog so if you're of age, and you should be if you're reading this story, go ahead and give them a follow!

Now, ENJOY!

Sans always enjoyed a bath after a long day's worth of work. Considering he worked as an escort, a bath was particularly soothing for his sore bones. Every day he fucked, at the very least, twelve different people any number of times. Needless to say, he always slept like a baby. How could how could he not? Truly he was living the life. There was nothing better than making one's living by doing something they loved and were, honestly, probably addicted to. Sans shrugged the thought off. Being addicted to sex wasn't so bad. It was much better than any form of narcotics or opioids.

The small skeleton sank into the bubbly water and drank in the gentle perfume of the soap. He adored the sweet scent of butter flowers. It was subtle and temporary – something that couldn't be said for lavender or lilac. He relaxed in the warmth of the water, offering his bones a chance to heal from the extended hours of merciless fucking. Sans closed his eyes and hummed to himself. He didn't notice Papyrus entering the bathroom until he was right next to him and, when he did, it gave him quite a fright.

"gah! papyrus!" Sans shrieked, his heart beating frantically in his ribcage. "geez! you scared the shit out of me!"

"Sorry." He chuckled as he leaned against the basin's rim, taking a seat on the ground. He extended his hand and trailed the tip of his fingers over the agitated surface of the water. "I thought you knew I was here."

"i didn't." Sans said leaning back into his comfortable position. "i thought you wouldn't be back home for a good few more hours. what time is it?"

"Hell if I know." Papyrus shrugged.

"something bothering you?" Sans asked.

"Nah. Just tired." Papyrus sighed. He bore the expression he typically did whenever a client he got too attached to broke it off with him.

"ah pap." Sans smirked, punching his brother's shoulder affectionately, "you're too much of a sweetheart. don't let them bother you too much."

"Fuck 'em, right?" Papyrus shrugged, forcing a smile.

"i'm sure you did." Sans grinned and winked. Papyrus immediately smacked his head against the tub's rim, groaning at the terrible joke. Naturally, the smaller skeleton couldn't help but laugh at the priceless reaction. "you walked right into that one!"

"I guess…" Papyrus grumbled, propping his head back up. Now he wore a more genuine and amused smile.

Better. Sans thought to himself with great satisfaction.

Sans breathed deeply and eased back into a comfortable position, tilting his head towards the ceiling as he began to relax again. It took him a moment to realise Papyrus was still with him and seemingly had no plans to leave. He peeked an eye open, side-glancing at his brother who was simply staring at him as his fingers trailed through the bubbles and water lazily.

"you just going to keep watching me bathe?" Sans asked, shutting his eyes again.

"Sure." Papyrus agreed with a shrug.

"well the least you could do is clean me." Sans joked.

"Fair enough." Papyrus surprisingly conceded.

So surprising, in fact, Sans jerked out of his relaxed position, snapping his gaze towards the taller skeleton. "pap, i didn't—"

"It's fine." Papyrus assured with a small chuckle as he moved behind his brother. "You're not getting much cleaning done yourself anyways."

He reached for the soap and sponge on the little ledge against which the bath was placed. Sans listened, mildly embarrassed, as his brother squeezed the liquid onto the sponge before placing the bottle back where it went and getting to work. Sans glanced down, watching Papyrus's hand move over his clavicle and thoracic vertebrae which he was steadily soaping up. His gestures were firm but smooth, applying the right amount of pressure for the circular actions to be enjoyable rather than uncomfortable. Sans found himself quickly easing into the touch. Perhaps this hadn't been such a terrible turn of events.

After a while of rhythmically scrubbing, Papyrus scooped up some water with his remaining hand to rinse away the soap that had frothed up. Once clean, he repeated the process, moving to wash Sans's arms starting with the humerus. It was very enjoyable and soothing up until the point Papyrus began to sponge his ribs and sternum. Sans, again, jolted out of his comfy position as sparks of pleasure were triggered by Papyrus's motions.

"What's wrong?" Papyrus asked innocently.

"s-sorry…" Sans stammered embarrassingly, "it's just…my ribs are…sensitive."

"Oh." Papyrus uttered in return and Sans took it as a silent understanding that he would henceforth avoid the area altogether or be more careful. The smaller skeleton consequently leaned back into position, hardly reacting when his brother's free arm draped itself over his shoulder and across his ribcage in a sort of strange hug. That was, until his other hand returned to the area that had snapped Sans out of his relaxation and began stimulating it relentlessly again. Sans's eyes jerked wide open once more as a choked moan squeaked out of his mouth. He tried to jerk away but Papyrus held him back as he continued teasing the sensitive spot. "So you're telling me…" Papyrus rumbled lowly, his baroque tone sending shivers down Sans's spine, "You like it when I touch you here but it embarrasses you…"

"n-nehh…no…" Sans moaned despite being heavily turned on by the way the situation seemed to be unfolding, "that's – ahh – n-not what i meant…"

"Maybe, but it's still the truth." Papyrus conceded, pressing a gentle kiss to the back of the other's neck.

"a-ah!" Sans gasped as he felt Papyrus's other arm beginning to move. It was teasing at his lower vertebrae, steadily inching closer to his pelvis. "was this your plan all along…?"

Papyrus did nothing but laugh lowly as he conjured a tongue and started licking his neck. Soon after, his hand finally reached his pelvis and began teasing. Thin but strong fingers kneaded into the bone just the way Sans loved it. However, it was done with such expertise that it was driving him mad. The pleasure the action sparked was unlike anything else and had him crying out for more as he lulled his head back.

"ahhn…pap…" Sans whimpered.

"Tired of the foreplay already?" Papyrus teased, "I thought this was your favourite part…"

"not true…" Sans whined, canting his hips slightly as he conjured an ecto pussy though beyond the borders of his free will and control. "it's…mm! – it's the worst—"

Another gasp and cry erupted from Sans as Papyrus's hand wandered to the freshly summoned ecto genitalia. His fingers pressed against it, easily finding the clitoris and teasing it. He milked a series of mewls and maddening whines from Sans as he continued his merciless ministrations there. The pleasure was starkly different from the one the smaller skeleton had been experiencing before. Where the teasing at his ribs and pelvis brought about the ghost and memories of a good, hard fucking, stimulating his clitoris intensified that in a way made the more direct pleasure all the more unbearable. The longer Papyrus continued to toy with the little pleasure button, the more Sans craved his cock inside him.

"papy please—" Sans begged. "i-i don't…i can't—"

"After such a long day of fucking at work," Papyrus purred and kissed his clavicle, "you're still desperate for something more inside you?"

"yes, please—" Sans moaned.

He then choked on a cry as Papyrus's fingers pushed into the opening of his ecto pussy and began thrusting in and out at a rapid pace. The pleasure had changed in nature but was just as insufferably teasing as what he had previously been subjected to. It felt good but it wasn't a pair of fingers he wanted fucking him, it was Papyrus's cock.

"That must feel better, hun?" Papyrus rumbled against the bone of his shoulder, his voice tickling the area. "Feeling satisfied?"

"no—" Sans grunted, though he couldn't help the desperate cant of his hips as he met each of his brother's thrusts that indicated otherwise.

"So needy, Sans." Papyrus chastised, clicking his tongue in discontent. "Don't be such a slut."

"can't…not with you—" Sans breathed in between moans of pure ecstasy. He was about to keep going when Papyrus's fingers suddenly jabbed at a particularly blissful spot. The sound that left him was lecherous and frankly embarrassing, but Papyrus seemed to enjoy it a lot as he began abusing the area in question without the slightest bit of restraint.

"Such a nice sound you made there…" Papyrus chuckled lowly, "I think I want to hear it again."

"papy, please!" Sans begged again, losing any shred of composure he had ever had. "i-i need you so much! i – ahn! fuck! mm…yes!"

"What was that, Sans?" Papyrus asked, evidently amused.

Sans tried to form words but the pleasure he felt as his special spot was so perfectly stimulated kept him from doing much else than moan and mewl. He gripped Papyrus's wrist in an attempt to stop him or slow his actions temporarily, but the moment he did, he realise he wouldn't be able to bear without the intense flow of ecstasy the fingers were providing him. Sans was being driven absolutely nuts.

"papy—i'm going to cum—" Sans moaned desperately. "p-please stop—"

"Stop? Do you take me for such a cruel monster?" Papyrus laughed. "I would never do that to you…"

"i-i want to cum with you inside me!" Sans cried out while he still could.

He felt Papyrus tense momentarily from his declaration, likely because the latter was taken by surprise. And suddenly, his thrusts were faster and harder, increasing the pleasure that was already driving Sans to insanity. It felt so good, but it wasn't enough. He needed Papyrus's cock but was going to cum without it, it seemed. Thus, the smaller skeleton moved his hands to grip the side of the tub as he continued to snap his hips wildly for more. He tilted his head up and cried out loudly when he was finally pushed over the edge and came.

Papyrus removed his fingers almost instantly after but continued to loom behind Sans until he caught his breath. At that point, he turned around to look at the taller skeleton with a confused expression.

"why did you make me cum?" He asked. "i wanted you to fuck me…"

"I didn't want to get in the bath." Papyrus shrugged as he rose from his seat. "Didn't feel like getting wet."

Sans watched him as he circled around the bath, steadily heading towards the door. As he moved about, the smaller skeleton managed to catch sight of the bulge in his brother's pants. "do you need help with that?" Sans asked eagerly, shifting his position.

"I suppose I could use that clever mouth of yours." Papyrus reckoned with a cheeky smile.

"actually, i was thinking i could just sit on it." Sans admitted bluntly. He may have cum, but he was still craving the other's cock inside of him.

"Drain the bath and I'll consider it." Papyrus replied, walking into their bedroom.

Sans wasted no time in pulling the plug and dashing out of the tub. He nearly slipped in his rush in part due to the water dripping from his bones, but also because his legs felt like jelly. He loved it when Papyrus got like this with him. Tonight was going to be a fun night.