Quote Originally Posted by The Archangel
Just a little theory, maybe the reason for Stein's rapid descent to madness is not only due to Asura's wavelength but also to that last attack from Medusa when they fought, that would also explain why he keeps seeing her everywhere.
I'm not too sure of this. Basically Stein, a body modifier himself, should be able to remove whatever Medusa might have injected into him - that is, if he wanted to, which is not given. So, his visions of Medusa might be either a simple result of madness or some sort of a connection he willingly chooses not to remove (Medusa is so hot that I wouldn't blame him).