Long ago, there lived two races: HUMANS and MONSTERS
One day, war broke out between the two races.
The MONSTERS fought ferociously, but the HUMANS kept coming, and never let up their assault. The MONSTERS were eventually overwhelmed.
What survivors remained were sealed deep in an inactive volcano by SEVEN DARK MAGES.
Many monsters tried to hold onto hope or positivity. But positivity dwindles, and hope can only be stretched so thin. Resentment and hostility, however, may begin to approach a boiling point as ages go by.
MANY YEARS LATER
MOUNT HALLEF
It is known that those who climb this "dark mountain" are never seen again.
(A child climbs up through the blackened path, coming to the summit, where a strange, deep hole resides. Reacting too late to stop themselves, they snag their foot on a strange vine, and plummet into the abyss. Though their life has most certainly flashed before their eyes, their fall has been broken, and their life saved, by a bed of red roses... Red, thorny roses. The longer they look up, the more distant the light seems...)
Note: Much like in Undertale, Frisk and a certain someone else are called "they" for the sake of headcanon, so feel free to call them whatever in reviews. I personally see Frisk as a girl, but I did want to keep it open to interpretation.