Season 2 Episode 07 - Intimate stranger
With a little help from Ares, Callisto manages to swap bodies with Xena so that she is in Xena's body and Xena is in Callisto's body. As Callisto was dead Xena, in Callisto's body, is now in the underworld but thanks to Ares she manages to become living again for one day. Callisto, in Xena's body, is trying to teach Gabrielle how to kill with her staff, just in case she sees "Callisto" again. When Xena and Gabrielle see each other Xena manages to persuade Gabrielle that she is not Callisto. After a clever speech about Gabrielle not dreaming since Perdicas died Gabrielle trusts Xena.
Xena soon finds out that Callisto's plans are to kill Xena's family the same way that Callisto's died, by burning to death. Xena manages to stop her with the help of Gabrielle and Joxer and sends Callisto back to Hades. Although Callisto has gone there is still one problem, Xena is in Callisto's body.