I have an idea for an Underfell explanation – When the humans sealed all of the monsters underground, they stole all of the monsters' SOULs as well, causing them all to lose all their senses of love, mercy, compassion, and empathy…all while retaining every single other traits. The lack of all these traits have caused all monsters to turn violent and start fighting each other out of nothing but pure hatred and anger…aside from that though, they are all completely 100% in-character. For example, Woshua tries to "cleanse" it's enemies by throwing bars of soap at everybody, Aaron tries to kill other monsters by flexing so hard that their minds can't comprehend and they explode. (So far, this has only worked on So Sorry, conveniently.) All of the monsters team up to kill the "greater evil" of Jerry. The only monster that was able to maintain their empathy, compassion, mercy, and love is Asriel, but it cost him his monster form, and he was turned into flower (Flowey) as a result…somehow. So, ironically, in this World, it really is "Kill-or-Be-Killed", and the only one wo doesn't believe so is Flowey. He used his powers of SAVE, LOAD, and RESET to try and find ways to redeem the monsters, but to no avail, so now, every time a human falls down into the underground, he tries to help them survive, and see if they can redeem everybody. Up to this point, it hasn't worked…Until Frisk falls down.

HOW DID YOU MAKE OMEGA FLOWEY CUTE