[Morgana]

“Sounds as if he may have been demonically possessed........
“

Or very mentally ill.

[MHGinTN]

Demonic possession is more likely since he could appear quite shy and normal when he had to to avoid exposure of his demented state.

[longfellowsmuse]

Indeed, it is often difficult to differentiate between the two.

[GeronL]

I agree.

One or both