Sans AU One-Shots

❀Nightmare❀ || staking claim.

Pairing: Nightmare Sans x Female Reader
Prompt: After he loses to his brother, Nightmare is pissy and needs an outlet for all that aggression. The choice is obvious when his sons think it's okay to flirt with you, and deciding he needs to remind them - and you - of your place, he stakes his claim over you for them to hear. 
Type: smut
Length: 4.8k words
Background: Nightmare's goop is canonically acidic, and though I typically don't include that in my work, today I decided to add that little piece of trivia ✨
Notes: The relationship between you and Nightmare is left vague so it's whatever you want (boss/minion, friends, lovers) but it's obvious you mean something to him - regardless of whether he'll admit it. | This is also kinkier than I usually write, but while vanilla is reliable, I'm trying to get better at branching out with my spice. (And the requestor specifically asked for some kinks so thanks to that lovely reader for that!)

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That could not have gone worse, and not only did this piss the King of Negativity off, but it made his normally slightly acidic goop downright toxic. The boys avoided him just like they dodged his glare, which he was more than happy to pin on any one of his minions that dared to glance in his general direction. He longed to teleport to a negative AU, soak it in like the warm rays of the sun, then go back to the AU where Dream just kicked his ass and set things straight. How could he have lost to his pathetic brother??

"How is it my fault?" Killer's voice butt into his thoughts, all kinds of offended without any justification to back it. "Dust sat on his ass when Baby Blue tried to attack me."

"I'm supposed to protect you?" Dust asked, a sharp glint to his eyelights as he grit his teeth.

"You saw I was sneaking up on Ink!" Killer's knife caught the light, dancing its reflection along the floor as his fingers moved with a practiced speed that made it impossible to follow.

Dust's socket twitched. "How am I supposed to distract Ink for you if I have to save you from Swap?"

Killer opened his mouth but Horror beat him to it, holding up a finger as he announced, "I smell something cooking."

"Yeah, my beef with Dust." Killer's smile stretched a touch too wide as Dust glared at him, but Horror was already walking down the halls in the direction of the kitchen. Nightmare snatched both of the boys by the neck with his tentacles before they could attack each other, and they struggled to get their feet under them lest he drag them down the hall.

"You idiots are the reason Dream continues to thrive in positivity. Do you not understand how important it is that we take that from him, or do you need me to show you how powerful emotions are as I beat all of you for losing to the Star Sanses?!" His voice rose with every word, the goop dripping off of him hissing as it plopped onto the carpet, and the minions fought to get free with yowls of pain.

Nightmare rounded the corner to the kitchen to see (Y/n) holding out her spoon to Horror, who took it in his mouth with an eerie grin. "You think it's done cooking?"

Horror rolled the broth around in his mouth before swallowing and nodding. "You're improving, (Y/n)." She beamed at that and Nightmare's teeth clenched, her positivity positively insufferable right now. Killer sliced Nightmare's tentacle with his knife and the severed end fell to the ground, dissolving into shadow as the King sneered, but Killer was already across the room and begging for attention from (Y/n). She startled at his sudden appearance then laughed, reaching out to rub his head affectionately, and Nightmare's tentacles writhed on his back, making Dust gasp for air. Her head snapped up and she gasped, rushing over to take Dust's hand and free him from Nightmare's wrath.

"Let him go, honey," she begged, sending the King a pleading look that earned her a spiteful scoff.

"Dust is aware of what he did - and how little any of them deserve mercy."