James Jacobs wrote:
Celeste's motivations in the Shackled City adventure path were never really adequately explained in the original run of the adventures in Dungeon, which is a shame. She was kind of a late addition to the mythos of that Adventure Path, and she wasn't really explained well.
Her true nature and motivations are detailed more clearly in the Shackled City hardcover; she's good aligned, but certainly not lawful. If, in your Shackled City campaign, you had her be evil, and you fear that using her in the Age of Worms will cause a weird disconnect with your players, simply change her name and you're good to go.
If anyone who doesn't have the Shackled City hardcover is interested, I can post a quick explanation here on this thread that describes why Celeste does what she does in that campaign.
Yes please that would be very helpful. I thought she was evil as well when we ran the original Shackled City Adventure Path and I never bought the hardcover, so it would be immensely helpful to me as DM to know a bit more about her. We aren't that far along in the Age of Worms yet, but we will be getting through last months adventure in the next couple of weeks so this info could be very useful.