Long ago, two races ruled over Earth: HUMANS and MONSTERS. One day, war broke out between the two races. After a long battle, the humans were victorious. They sealed the monsters underground with a magic spell, beneath the imposing Mt. Ebott.
Legends say that those who climb the mountain never return.
With a start your eyes shoot open. Sunlight spills through a large hole quite some distance above you, and you blink reactively for a second. Your ears ring with a sound you can't quite identify. You sit up and look around. You can't see much of your surroundings, but it's clear you've found yourself in a cave of some sort. The only pop of color in this room is the patch of golden flowers you're lying in. They're surprisingly soft and cushy to the touch; you reason they must have broken your fall. Standing up, you walk into the darkness a bit, your eyes adjusting to the underground setting, and start exploring the cavern. There is only one exit you can see, so you follow the path until you arrive at an ornate doorframe, emblazoned with an odd sort of triangular symbol.
You walk through it enter another chamber which, like the one you fell into, has in its center a small circle illuminated by sunlight. In the center, however, is not a patch of golden flowers, but one, solitary bloom—and one that looks rather worse for the wear. As you approach curiously, it speaks.
"Please don't kill me."
The voice is sad and broken, and for the first time you notice the semblance of a face, ringed by ragged, yellow petals. This flower looks as though it has been on the receiving end of far too many beatings. It repeats itself.
"Please… what did I ever do to you?"
As it turns to you and gazes into your eyes, an odd sensation washes over you—or rather, two. You feel a sudden urge to kill this poor creature, but at the same time, a voice seems to tell you to have mercy on it. You stare for a moment, overwhelmed by the sudden position you have been placed on, and then, as if you were pressing one of two buttons, you decide to spare it.
The flower, who had been shaking and cringing in anticipation, looks up in small shock. "You… you're sparing me?" it says, incredulously. "All this time and I've never seen anyone do that before." You don't reply, standing in front of the flower until you believe it's sure you have no intention of harming it. It now looks intrigued, and realization dawns on its face. "You… you must be new to the Underground, aren'tcha?" His voice—it somehow feels right to refer to this being as male—has lost a bit of its frightened, resigned tremble, and is now distinctly more… well, friendly. "You must be so confused."
The look on your face must confirm his statement, as he nods and says. "I'm Flowey. Flowey the flower." He flashes a smile as he introduces himself, and you feel as though this plant might just be your new best friend. At any rate, he's the only one you have for the time being. "Someone ought to show you how things work down here… I guess I'm good as any." Flowey's smile fades. "Listen… this is not a good place to be for a human like you. These ruins are filled with monsters, and every last one of them will not hesitate to kill you. Worse still, there's her to worry about…" Whoever he's talking about causes him to visibly tremble in fear again.
He looks at you and smiles again, though you can't help but feel that this one is a bit forced. "But don't worry about it, alright? I'm going to help you back home. That's what friends are for, right? Now follow me… and be very, very careful." With that, Flowey disappears beneath the earth and appears to travel quickly in direction of a door similar to the last, but much larger and, somewhat troublingly, colored a dark shade of red. Apprehensive, but trusting your new friend, you walk through.
The darkness that prevailed is gone and you find yourself in an antechamber of sorts. Flowey is ahead, using vine-like tendrils to activate what appear to be four switches on the floor. "These ruins are full of puzzles and traps… but they're not the most dangerous part. I can handle them." The door at the opposite end of the room clicks open and he once again vanishes into the soil. On the other side of the door is the entrance to what appears to be a desolate city. The ground is littered with fallen leaves—appropriate, you decide, considering your method of arrival—and everything from the floors to the roof is that same, ominous shade of red.
Looking up at the ruins, you feel something within you. The sight of this building looming in this underground place fills you with determination. You almost seem to glow with a bright light, and suddenly you once again hear the source of the noise that echoed in your ears when you fell. It once again echoes, resonating within you, a single word: Chara.