There’s an old TSR module “The Vortex of Madness and Other Planar Perils.” Basically, on the ethereal plane, is a trapped entity. That entity turns out to be a combination of the old Greyhawk villain Baron Lum and the Machine named after him that has gained a form of sentience for itself.
The adventure starts with the characters living through creepy dreamworld versions of Baron Lum’s formative years and experiences, and then with running fetch quests among the planes for the Machine (possibly in the furtherance of its burgeoning sentience and exploring its capacity for free will and self-determination).
My plan: use the whole thing, but swap Tithian for Lum, ditch the machine, replace the Hollow for the vortex of madness. Players run through Tithian’s greatest hits of formative memories.
At the end of the original adventure, the Machine finally lets Lum loose (it had him trapped within itself and was feeding off / in a symbiotic relationship with him), and he attempts to commit suicide-by-PC, driven insane by the experience. There was the opportunity for the PCs to rehabilitate him, and maybe he learned from the experience?
Here, Tithian would have learned from his experience and ultimately take the part of a mentor for the players.