False host (undertale fanfiction)

Chapter 2:Threads of Violence

Sans was getting used to the strange presence inside him. At first, he thought it was just exhaustion playing tricks on him—staying up late, the usual laziness creeping in—but this was different. It was persistent, always there, lurking at the edges of his thoughts.

He didn't know where it came from, only that it called itself a system, as the error window had once said. It had appeared out of nowhere, with no explanation, and ever since, Sans had felt it worming its way deeper into his mind

"Sans! Open the door! You shall experience the culinary perfection of my glorious spaghetti!" Papyrus's booming voice shook the walls from outside.

Sans chuckled, though his humor felt more automatic than genuine. He raised his hand lazily toward the door, planning to open it with his powers like always. But something went wrong. The familiar blue aura that surrounded his hand flickered, then changed. A swirling red seeped into the blue, the two colors mixing like oil and water.

"What the—" Sans muttered, frowning as he stared at the unsettling new glow. It was faint, barely noticeable, but the sight of it chilled him.

Before he could dwell on it further, the door creaked open on its own. Papyrus stood there, proudly holding a steaming plate of spaghetti. His grin was as bright and enthusiastic as ever.

"Sans! You're late! The spaghetti will cool, and that would be a culinary tragedy of monumental proportions!"

Sans waved off the concern, trying to ignore the lingering unease in his chest. "Thanks, bro. Looks like you made... a spooketti. Scary stuff."

Papyrus gasped dramatically, clearly unimpressed with the pun. "Sans! My spaghetti is never scary! It is only to be eaten with respect and admiration!"

"Sure, bro," Sans muttered, taking the plate. He wasn't hungry, but he couldn't say no to Papyrus.

As Papyrus launched into his usual tirade about the artistry of spaghetti, Sans' mind drifted. His thoughts kept circling back to the strange shift in his powers. He glanced down at his hand, but the red particles were gone. Still, he couldn't shake the image. Red and blue, intertwined, like some corrupted version of the power he'd always known.

Papyrus's voice pulled him back to reality. "Sans! Are you even listening to the majesty of my words?"

Sans smiled, forcing himself to focus. "Yeah, yeah. Best spaghetti in the Underground, right?"

Papyrus huffed but seemed satisfied. "Of course! But don't let it get cold. I'll be in the kitchen perfecting my next dish!" With that, he dashed away, his cape fluttering behind him.

Left alone, Sans set the plate down and stared at his reflection in the nearby mirror. His sockets narrowed as he looked closer. His usual glowing blue eye had a faint red tint now, like the particles he'd seen in his hand. His stomach churned.

"What the hell is going on with me?"

He tried to summon his power again, raising his hand and focusing. The aura appeared instantly, but there it was again—the same red hue, swirling within the blue.

Sans stepped back from the mirror, uneasy. Something had changed, and it wasn't just his powers. He felt it deep inside, like an itch he couldn't scratch. His emotions, usually so calm and controlled, felt frayed, on edge. Anger simmered under the surface, a constant hum in the background of his thoughts. It wasn't like him, but lately, he couldn't seem to shake it.

He glanced at the error message that had started appearing in his mind since the system fused with him. The menu hovered before his eyes, showing three options. Only the 'Items' tab was unlocked; the others were grayed out, marked with a message: Not enough determination.