[SPOILER] Plot Discussion Thread *Spoiler Alert*

[PathOS]

Mandus also tells the Professor that "I am merely a Conduit"

In the March 1899 note he also speaks of how he can only hear the "voice within the gentlest of stones. It sings to me and I dream of a great machine."

Later he talks about how he'd set the stone on the mantle and then proceed to "recraft" (massacre) the servants of his household. Burying their skulls in the garden. (funny allusion to an earlier note, possibly a loading screen note, that talks how upset Mandus got when someone suggested to remove the Rhododendrons, where he buried them)

It definitely sounds like there was a presence within the stone/orb that took a hold of him. Or the orb created a second persona within him.

In fact, just after you find this note the Engineer recites it to you in the Core systems, though speaking now from "his" point of view "and you put me atop the mantlepiece and set upon recrafting the servants, and you buried them in the garden alone"