It was a warm summer day on the surface. Frisk quickly made his way down the road, on his way to his friend Alphys' house. An "ailment" had begun to afflict him; a certain part of his body would grow stiff with the most innocent of stimulation. It was beginning to cause frequent embarrassment, and even things such as Toriel's more womanly features would cause a reaction. He would then have to hide himself and desperately attempt to will it back down. Not knowing what to do, he decided that his scientist friend would be able to think of a way to make it go down quicker. At least, that was what Frisk had tried to tell Alphys. When he had lifted his shirt in the middle of his story, the sight of the child's erection tucked up into his waistband had her blood rushing straight to her head. Alphys stood there wide-eyed, mouth slightly agape as she stared at his dick. Pink flared in her cheeks as she blushed from the sudden exposure. Her first thought was to deflect the inquiry to Asgore and Toriel. It only made sense that the child's foster parents had "the talk" with him. That thought was washed away by a much stronger feeling. Images of the human art known as "hentai" flashed before her eyes. She had spent countless nights in the underground, fingers buried deep within herself as she lived out fantasy after fantasy through her monitor. A particular genre had sparked an interest in her that she could not explain. Images and car-toons depicting young boys with grown women had intrigued her like nothing else had. She had thought it would be something she could only experience in fantasy, but with an opportunity presenting itself like this, how could she pass up the chance to make it reality? "Y-you, uh.... You want to know h-how to make it go d-down?" Alphys asked, her nervousness caus-ing her to sweat profusely. Frisked nodded, and she swallowed the lump growing in her throat. It was now or never. "Alright, I c-can show you. But, uh, we s-should probably go up to my room first." Frisk let his shirt fall down, and crossed the threshold into her home. She closed the door behind her, making sure all the locks were engaged. Taking Frisk by the hand Alphys led him to her room, giving her bedroom door similar treatment to the front. "S-so the first thing you want to do is.... uh... g-get n-n-naked. You don't always have to! B-but it will make things easier the f-first time..." Alphys said. As trusting as ever, Frisk strips in front of her. A pile of clothing is created in the corner of the room as he tossed his clothing to the side. Alphys takes a moment to glance at his body before getting on her knees in front of him. Eager to get to the good part, she gives him a quick and basic explanation of his erection. She tells him that in order for it to go down he has to cum, which happens after his penis is stimulated enough. She demonstrates this by grabbing his shaft lightly in her hand, pumping it slowly up and down his length. Frisk let out a soft gasp as the scaled hand pumped at his shaft. Alphys noticed that Frisk seems to be enjoying himself, and asked him if he wants to feel even better. Frisk nods eagerly, and Alphys stands up and begins to disrobe. Easily slipping out her dress, she ex-posed her orange body to the child. She crawled on top of her bed and lied back against a stack of pil-lows at the head. Alphys motioned for Frisk to move onto the bed with her, and has him straddle her tail with his head between her legs. She hooked two digits on either side of her pussy and spread her-self open, showing Frisk the fleshy pink tunnel within. The excitement of what was to come had been constantly working her up since Frisk had revealed himself. The involuntary spasms and dripping arousal were a testament to that. "S-so, uh...even though girls have pussies instead of dicks, we can still cum. When boys put their dicks in here, it feels REALLY good for both of them." Alphys was sweating harder than ever. She could still back out now and nobody would have to know. The burning lust in her loins won over logic, and she whimpered, "D-do you w-want to cum with m-me?" She was shaking, staring at Frisk's face worried about how he might respond. Her anxiety was turned to excitement as he smiled and nodded his head. "R-Really?!? Awesome!" She moved her hands to her thighs. Frisk scooted up, placing each knee at the base of her tail as he aligned himself at her entrance. He looked up at her. "Just...push it in!" she said, blushing heavily. Frisk nodded and they both looked down. He began to push forwards. Her folds resisted him for a mo-ment before he broke through and sank fully inside her. Moans rang out as their hips pressed flush to-gether. While Undyne loved to eat her out, battle tacos, or fuck her with numerous different objects, Alphys had never experienced a real dick before. Unique in texture and shape, its warmth and subtle twitching in tune with Frisk's heartbeat made her own heart flutter with excitement. "Ah...F-feels good, right? Now you gotta start moving it. Just pull it all the way out until only a little bit in is, then push it back in. Once you figure it out, you can go faster!" Frisk placed his hand on her waist to steady himself, and began to pull out. The friction caused both of them to moan again, and Frisk instinctively bucked back into her. "H-Hey! C'mon, you gotta pull out more than that!" Frisk, looking DETERMINED, tried again. This time he withdrew until just his tip remained inside her, then buried himself back to the hilt. "Oh! Y-yeah....just like that!" Frisk repeated the motion, and quickly picked up the rhythm of fucking the big lizard monster. Although the situation was playing out exactly like it had in her fantasies, there was one more detail Alphys needed to make it perfect. As Frisk continued to thrust into her pussy she reached forward and embraced him in a hug, placing one hand on his back and the other on his head. He was just the right height that his head rested between her breasts, and she moved her shoulders forward to sandwich him between them. He looked up at her, pleasure showing through the usually stoic face. She stroked his hair. "K-keep going, y-yyou're doing great!" The lewdness of the situation playing on her mind combined with Frisk's eager thrusts were soon too much for Alphys, and she threw her head back. Gasping and squeezing Frisk tighter, she came. Pleasure raced up and down her spine as her muscles pulsed along Frisk's dick, milking the child for all he had. Frisk, unaware of Alphys' state, continued to saw himself through her orgasm. Stars burst in her eyes as she was over stimulated, and continued clutching the child as she rode out the pleasure. Her arousal drained on the sheets beneath the pair, Alphys came down from her bliss. That bliss, how-ever, was replaced with something she was all too familiar with: post-orgasm shame. She immediately began to worry, any and every consequence she might face playing through in her mind. "What the HELL am I doing?" she thought to herself, "This was a stupid idea to begin with! I should just..." Alphys' thoughts were interrupted by Frisk calling out her name, hugging her tight and hilting himself. Her eyes shot open as she realized what was about to happen, but only managed to squeak out "W-Wait!" before she felt the first throb as he came inside her. Rope after rope of the child's first orgasm was flung against the back of her tunnel, quickly filling up her womb in a futile attempt to impregnate the monster. Alphys gasped as Frisk filled her up with his warmth; this was the moment, she would re-alize in the future, that she had became addicted to the raw, carnal pleasure of having a male unload every drop of cum he had directly where it belonged. Exhausted, Frisk collapsed onto Alphys. Mo-ments later a quiet snoring could be heard as he slumbered atop her body. Alphys' face remained frozen in shock as the gravity of the situation weighed down on her. What was she going to do? If anyone found out about this.....Undyne...Asgore and Toriel, who knows what they would do... Frisk's shaft had softened enough to slip out of her, and she shivered as she felt his cum slide out of her, over her asshole, then down the sides of her tail to join her stains on the sheets. She turned her head to the side, glancing at the location of one of the many cameras that had recorded the event. A lewd smile crept over her face. "Well, at least I've got new fap material!"