Or to make it palatable, establish an uneasy relationship between her and the natives. Some have come to rely on her too much, some want to expel her somehow from the area, some have fled to neighboring tribes and live as self-imposed exiles. Fantomah is not a pleasant Mary Marvel type, and the natives would have a variety of reactions to her. I'd try building them up as characters and leave Fantomah enigmatic and capricious-- sort of like the Greek gods.