I always find myself depicting Evat as a calm, deep thinking thing. While those deceptions of him are true, for the most part, it fails to show his other side.
Evat was executed and imprisoned in the underworld for crimes of kidnapping and raping an immortal being with the equivalence of a child.

And so I can safely say... he's not quite sane. He is looked after by his sister Ki, who assures he won't free himself of his bonds.
The bonds on his face are suppose to keep him from speaking, but in fits of rage he can pry them open to scream or babble something in a dead language.