So. Permissions post time.
> Zagreus is sort of a ball of telepathic, invasive, bad feelings...ness. He can't corrupt or infect people or places here, but he can still manage a touch-telepathic connection on normal people (closer to the brainmeats, the better) and a more generalised field-of-feelings telepathy on time-sensitives, natural telepaths, etc, sans touch, though naturally it'll be more effective with. Both of these require some degree of effort, less so if he's tetchy (or, you know, homicidal) and mental fortifications are certainly possible, though they'd be a bitch to learn, for a human.
> If you think his metaphysical presence would get under your character's skin, please let me know.
> If he can dig through your character's mind for information, he'll certainly want to. Can he, should the chance arise?
> He's really not very nice, and given access to someone's mind, even with the caveat that he can make no lasting changes or effects...he might do very awful things while he's there. His mind is a horrible, antithetical thing, and though he can manage to be businesslike with it, that's not...its default setting. It would be a jarring experience at best and if he's vicious for some reason, it can be a lot worse. If this sounds like your thing...hey, I'm not here to judge.