Frisk would not say he was superstitious. He would often dismiss such nonsense with a, "bah humbug!" But in a world with monsters and magic it never hurt to be too careful. So he left all the lights on when wandering through his house, just to be sure.
"Is little Frisky afraid of the dark? Don't be such a crybaby."
For the second time that day, Frisk jumped and whirled around. There was no one there. It was just the wind, just his imagination. Maybe a cup of tea would soothe his nerves.
He shuffled to the kitchen, flipping on all the lights and checking behind every door as he went. He finally reached the pantry and rooted through the junk. Pasta, beans and cans of who knows what. Chocolate that expired a few months ago. He pulled out a box of Golden Flower tea, Asgore's favourite (his favourite). Frisk put the box back and pulled out a different one. Earl Grey would do nicely.
"What a waste of perfectly good chocolate."
He knew he heard it that time, and he knew the voice. There was a butchers knife on the kitchen table, her favourite knife. He knew it wasn't there before. He picked it up, to use if needed. It's still kill or be killed, that rule is always the same, even when the others aren't. Especially when the others aren't. He knows that.
He also knows that she's dead.
"So you really were listening." It was hard to tell if the voice was surprised, pleased or disappointed. Maybe all three, not that Frisk really cared. "You idiot, you know I'm a bad influence."
He was ready for it this time, he backed up against the wall so nothing could spring up behind him. "Show yourself." His voice was steady and commanding, betraying nothing.
"As you wish, partner." The potted plant on the desk shuddered, then it ruptured, soil splattering the desk as the apparition clawed its way out. Vines clung to its form like shackles, chaining them to the ground. Flowers blossomed like ghoulish grins, their golden sheen making the spirit look terrifyingly beautiful. "Miss me?"
Without a word Frisk put down the knife and went back to making tea like nothing had happened.
"Aw, come on," the apparition teased, "is that any way to treat your long lost twin?"
He ignored it, pouring the scalding hot water into his cup. "Hello?" The ghost hovered over his shoulder, none to pleased with being ignored. "Hey! Listen to me when I'm talking to you!"
It nudged the kettle, splashing the boiling water over Frisk's hand. He couldn't help the cry of pain that escaped him. It's face twisted into a malicious smile, then morphed into one of horror and regret. It drew back, a good ways away from where Frisk was nursing his injured hand.
He finally responded to it's rhetorical question. "You're not my twin."
"Of course I am. Who else would it be?" The ghost spread it's hands, pouting, almost seeming hurt, though the slight smirk betrayed otherwise.
"I don't know what you are but my sister is dead. Ghosts, spirits and other such nonsense don't exist." He quickly added, "ghost monsters don't count."
She drew closer, "oh, so if I were a monster you would be fine with it? Should have sent Asriel then..."
"DON'T bring Asriel into this!" He snapped. "That's not what I meant and you know it."
"What am I then?" She smirked.
"A figment of my imagination."
She snorted, leaves rustling with every movement. "Your imagination isn't that good. You can see me, hear me. I bet you can even smell me." She waved her hand in front of his face, the scent from the golden flower on her wrist clogging his nostrils. "Why do you doubt your senses?"
It was true, there was no mistaking the distinctive, overpowering smell of the golden flowers his father loved. Still, he picked up his cup and walked right through her to prove his point, ignoring the chill that swept across his skin as he did so. "The senses can be easily tricked. Your just a bit of...indigestion. A spot of beef or a glob of mustard. Yes," he hissed. "There's more of gravy than of grave about you!"
"More of gravy than of grave?" She giggled, "leave comedy to the skeletons, Frisky bits!"
"Shut up." He snarled, not wanting to bring any more dead people into this.
"Afraid? Who would have thought it, a sinister old miser like you quaking in your boots." She teased, almost looking a bit melancholy.
He sat down in his oversized armchair with a huff. "I am not quaking-"
"Sure..." She rolled her eyes.
"-nor do I have boots." He ignored her. "As for being an old miser...well that's your fault now isn't it?"
The sadness that had been tailing her finally caught up. "I'm sorry."
He startled so bad some of the tea spilt into the saucer. He looked at her with wide eyes, "now I know you're not my sister."
She gave a bark of laughter, "what can I say, death changes things. Certainly gives you a new perspective. Do you know what these are?" She held out her arms.
"Your hands?" He deadpanned.
"No, stupid. The vines. What do they represent?"
"Nothing, because you're a hallucination." He said.
"Were you always this stubborn?" She frowned. He glowered back. "Right, silly question. They're my sins."
"How arbitrary."
"Hardly. See this?" She pulled on a flower, "this one is for forcing you onto my path, turning you into a miserable old miser. And this one," she tugged at a leaf on her ankle. "Is for that time we evicted an entire orphanage! They're all here Frisky, every single money grabbing, filthy, backstabbing moment. Every time, every crime, every lie you told yourself. Every kill, every thrill you got from seeing them suffer. This is my punishment, and if you continue along the path you are now, it'll be yours too."
"Humbug." He whispered.
She laughed bitterly, "still don't believe me? You wear such a chain yourself!"
She grabbed at the air and was suddenly holding a translucent vine. Frisk choked and grabbed at his neck, cutting himself on the thorns. He couldn't breathe! He couldn't move! Karma circled him, trying to drag him back into the earth.
"It's hell, Frisk, and you lit the pyre."
"St-stop!" He rasped. She let go. He gasped for breath, it was gone from his vision but it hadn't left, not really. He could still feel the thorns prickling across his skin, crawling on his back and weighing down his neck. "Fine. I believe you. How do I get rid of it?"
"Get rid of it?" She looked amused, "Do you really think you're above the consequences? That all the harm you've done can just be erased?"
"Why else would you be here?" He asked.
"To see my dear brother?" She laughed at the face he made. "Alright, there is a way. It's rather simple: just be a good person. Though, to be fair, that's easier said than done."
It was his turn to laugh. "Me? A good person? You're right, it's hopeless. I'm irredeemable."
"That's not true," she said, landing next to him. "Even the worst person can change, you could be good if you just tried. Or at least, that's what Papyrus thinks. Asriel did too. And once upon a time, so did you."
"I was an idiot. It's kill or be killed." He repeated the mantra that had been beaten into his head, staring daggers into the tea. The vines circled tighter.
She sighed. "I was wrong, Frisk." He didn't look at her. "Please, you still have a chance to be better." Still nothing. "Just take it!"
Nothing. Her vines became tighter, receding into the ground. She paled, the doctor was getting impatient. "I'm running out of time, you have to listen to me!"
Still no response. She was practically tearing her hair out with frustration.
"Brother, please, just take it!" The ground split open beneath her in anticipation of swallowing her back into the depths of hell. "I'm sorry, alright?!"
He refused. She strained against her shackles.
"Frisk..."
...
"Fine." She choked out. "You know what? You may be stubborn but I'm even more so. You have one last chance. Tonight, you will be haunted by three spirits."
"I've already had enough of that." He stiffly spoke up.
She ignored him for a change, determined to finish her message. "expect the first ghost tonight, when the bell tolls one!"
"Can't I meet them all at once and get it over with?"
"When the bell tolls one!" She screamed as she fell, finally loosing her footing. "CHANGE!"
The ground sealed up behind her. Then everything was as it used to be, except for a cold cup of tea and a badly shaken Frisk.
Yet, despite everything, he was still determined.