Originally from here, this page is supposed to give an in-universe insight for the disappearance of this incredible AU.
Floratale is a mysterious AU that not much is known about, as when Rhosaith had discovered the AU, the only life-forms left were flora. There was most definitely evidence of a civilization, but the reason for their disappearance is absolutely mysterious. Rhosaith has moved the AU to the Rho Exclusion Zone while research is being conducted into it.
- An entity known as Flora!Frisk. According to the recovery movement, Flora!Frisk is a fusion of Frisk and Flowey. According to documentation, this happened when Flowey was fatally attacked by some Humans, and Frisk "absorbed" Flowey, turning Frisk into a half Monster, half Human creature.