At the end of Wicked: Part One, Glinda and Elphaba separate after the latter decides to head west and devote herself to one day stopping The Wizard of Oz’s cruelty. Fans are thus surprised.

Elphaba and Glinda begin as enemies in the loose adaptation of Gregory Maguire’s novel, “Wicked,” which was itself based on L. Frank Baum’s “The Wizard of Oz.” The former witch is ...