How You Play the Game

Demonic

Mark trotted along through the tunnel, leading Jack by the hand. He stopped at a large gate-like structure opening to another area.
"Someone must live here or something. Why else would there be such a huge arch?" He observed, rubbing his fingers on it. It was solid, and an odd shade of purple. He shrugged. Bad guys wouldn't paint their arches purple, would they?
Sean, remember anything yet?
Jack shuddered, which went unnoticed by Mark.
They stepped through and saw natural light filtering in on one spot on the floor, like a spotlight almost. There was a smiling yellow flower sitting in a patch of grass under the light. When the two boys got closer, the flower smiled invitingly and began speaking.
"Howdy! I'm FLOWEY. FLOWEY the flower!" He introduced himself politely.
"Wonderful name you have there." Mark replied sarcastically. Jack giggled.
"Aww, that's adorable!" He exclaimed, looking at the flower. It smiled again.
"You're new to the underground, aren't ya? Golly, you must be so confused!" Flowey chuckled.
You shouldn't be, Sean.
Jack was getting better at ignoring the voice and not reacting, but everything it said still shook him to the core.
"Actually, yes." Mark nodded, stepping forward so Jack was behind him and farther from possible harm.
"Someone oughta teach you how things work around here! I guess little ol' me will have to do!" Flowey offered.
"Oh, great! Maybe he can help us get out of he... Huh?" Jack looked down, confused. They were both holding small red hearts, although Jack's had a black stripe running through it.
"How odd." Jack said simply, unable to truly comprehend the situation. The flower stood nearby, watching them.
"That is your SOUL, the very culmination of your being. Right now, it's very weak. But you can grow strong if you gain a lot of LV." Flowey explained.
But you already know that, don't you, Sean?
"LV...? Level?" Mark guessed, scratching his head. He poked his red heart, and his body felt tingly and weird. He disliked the feeling, and decided not to poke it again.
"What's LV stand for? Why, LOVE, of course! Don't worry. I'll share some with you! You want lots of LOVE, right?" Flowey giggled. Jack smiled excitedly.
"I'd love some love!" He jumped up and down happily. Mark, meanwhile, was more suspicious. He placed a hand on Jack's shoulder.
"Be careful, buddy." He warned.
"Why? He seems like a nice guy!" Jack complained.
"Down here, LOVE is shared through... Little white... "Friendliness pellets". Move around! Get as many as you can!" Flowey grinned, producing the so-called friendliness pellets and sending them spinning towards the two. Jack started running towards them, heart in hand, but was pulled back by Mark.
"Jack, listen to me, those look a lot like bullets." He whispered in Jack's ear.
"C'mon Mark, we're going to miss them! The flower just said that they're friendliness pellets!" Jack whined.
Oh come on, Sean, you know they're not.
"Look, if we miss them, he's just going to send them out again. If nothing changes, you can try to catch them. Please, just try it for me." Mark pleaded quietly. Jack looked at Flowey uncertainly, before nodding at Mark. This could be a chance to test out the voice in his head, too.
No need for tests, silly. You know it's me.
"Fine, if it'll prove how irrational you're being." He retorted, to either Mark or the voice we'll never know. Both males stood watching the pellets pass them by. They turned and looked back at Flowey. He smiled again, but it turned into more of a smirk. Jack noticed, and a look of confusion passed his face.
"Hey, buddies. You missed them. Try again, okay?" He sent the pellets out again, and once again Mark and Jack dodged them. Jack didn't protest this time, it was obvious something was off.
"HEY. Are you DEAF or something? RUN. INTO. THE. BULLETS. Er...friendliness pellets." Flowey glared at them. Jack shuddered.
"No way, h-he just called them bullets!" He squeaked, hiding behind Mark. As the third round of bullets passed them by, Flowey started twitching oddly.
"You two know what's going on, don't you." He growled, his face turning menacing.
"You just wanted to watch me SUFFER." He exclaimed, smiling grimly.
"N-no, we never-"
"We were just-"
"DIE." Flowey cut them off, circling the two males with a spray of white bullets. He laughed maniacally, his victory all but assured. Mark and Jack shuddered in fear, Mark crouching down and shielding Jack with his body.
Don't be afraid, Sean. Here she comes.
Then, the bullets vanished, almost as if they'd never been there in the first place. Flowey's cackling ceased and he looked confused. Suddenly, a large fireball hit him square in the stem and he was sent flying. Mark and Jack looked up to see an odd goat-like woman smiling gently down at them.
Do you remember her, Sean?
"What a terrible creature, torturing such poor, innocent youths. Do not be afraid, my children. My name is TORIEL, caretaker of these ruins. I pass by every day to see if any humans have fallen down. You are the first to arrive in a very long time. Come with me, and I shall guide you through the catacombs." She offered generously, smiling patiently. Mark didn't feel anything off with her so far, so he decided to be less suspicious.
"Alright..." He nodded slowly. Jack smiled happily.
"Oh my god, we're saved! We were about to die there, but she saved us!" He exclaimed in relief.
"She's got to be a good guy, for sure!"
It's a shame you have to kill her, Sean.
Mark looked at Jack in doubt, before smiling lopsidedly. He grabbed Jack's hand gently and followed Toriel, listening quietly as Jack pointed out the scenery, trying to forget the voice. It was very beautiful, purple and red mixed together to form an elaborate underground tunnel system. As Toriel prepared to pass into another room, a large glimmering star-like shape caught Mark's eye.
"Whaaaaat?" He looked at it in confusion, poking it. A small light emitted from the star, wrapping itself around his heart, which was still held in his hands. All of a sudden, he felt his body feel lighter and stronger. He also felt...something else. He couldn't quite describe it, it felt like someone had taken a photo of the exact moment, and tucked it away for later use.
This is a SAVE point, Sean. Remember it? It was so helpful when we were killing everyone. I can't wait to do it again.
"File saved." Jack said absentmindedly.
"Huh?" Mark looked at him quizzically.
"Ah...oh, it's nothing." Honestly, Jack didn't even know what he was saying. But he still couldn't drown out that small, quiet voice. Who was it?
I think you know who I am, Sean. You just don't want to remember.
Jack shook his head. Mark looked at him worriedly.
"Are you okay?"
"I'm fine, we should follow Toriel."
"Are you sure? We can take a break if you-"
"I'M FINE! I'm fine, just..."
Mark looked hurt for a second, before he shook his head.
"Right. I shouldn't have bothered." He said bitterly, pulling Jack along. Jack knew this was his fault, knew he should apologize, but he couldn't get over what he'd just heard.
Now I can kill Mark properly.
Whatever happened, he had to make sure Mark stayed alive. But he had no idea how to do that, when the only thing he was good at was killing.
That's right. Why bother SAVING anything? You'll never beat me anyways. Why do you think you're trapped down here again?
Jack gasped, collapsing onto his knees and convulsing wildly. Somewhere, the owner of the voice was watching and laughing madly as the black stripe on his heart grew.

A/N: Hi guys! I understand there are certain aspects of the Undertale game that I cannot capture properly, such as the fourth-wall breaking, the save points, and the HP and such. I apologize, but for the angle I'm going for it just wouldn't work. There might have to be some inferring and filling in the blanks, as all the cool little Undertale tricks can really only be experienced when one plays the actual game. Also, sorry if I botched some of the dialogue, didn't mean to.