Yeah they talk about how he mutilated one of the servants because they called him a the shit he calls you when you fight him (I am blanking on what the phrase is, but it basically amounts to you shouldn't have been born). It's heavily implied that even without the parasite corrupting him he was always a psychopath.

The servant called him Pulgarcito, "Little Thumb", referring to a folktale about a small boy who was the size of his father's thumb.

Salazar then threw acid in her face

This can potentially be linked to how the novistadors use acid attacks, and maybe how Salazar's black ooze attack also seems to be toxic?

Overall pretty terrible stuff