Prey
Elphaba was tired of being hunted. Constantly looking over her shoulder, painstakingly covering her tracks, it was exhausting. Often she found herself yearning to return to her days at Shiz; she may have been taunted, but she wasn't an outlaw.
The Wizard's offer was too tempting for comfort. Momentarily she allowed herself to slip into the delusion that all her problems could disappear, her slate could be wiped clean.
But if she wasn't the prey, someone else would be, and she didn't want that either. If she wanted to take down the Wizard, this was how it had to be.