Arielle is a being of power who used to work with Bill Cypher until they had a falling out and fought,Arielle almost one but Bill ended up using a few new tricks,she ended up leaving the plane Bill lived in she called home and fled to the human world into gravity falls,she's a witch who can shape shift into anyone or anything,even her own body,she lives in a shack in the woods not too far from the mystery shack,she also came across one of the three main books