Anya first came to Sunnydale to
grant the wish for Cordelia.

After wielding the power of the wish
for a thousand years her powercentre
was destroyed by Giles in an alternate
reality.

Anya is now a part of the Scooby
gang and was very much a part of
Xanders life until recently. Xander, after
being shown a vision left Anya at their
wedding. This resulted in Anya's return
to vengeance and becoming a demon.

Even though this new change has affected
her relationship with Xander she still runs the
Magic Box and continues to participate with the
rest of the scoobies.