Flowerfell is a timeline where Frisk fell from the surface and was infected with the  buttercups (Very poisioness when consumed) Frisk had the ability of reset and when she did buttercups covered her face she eventually died using her soul to break the barrier but Sans and Lucy don't live far from the mountain and sometimes stay inside the underground. 
Lucy's right eye can turn in a deep red when threatened and scared she can use Gaster Blasters, Bones, Teleportation like Sans