I rewatched some play throughs and saw that in some parts of dialogue, Rambley's eyes turns into a blueish green. As we all know, Rambley's original eye color is purple.

When the color changes, some sort of green electricity zaps him into a very temporary daze.

Then it changes color briefly.

As it was confirmed by UniqueGeese, Rambley is definitely not evil. But I think this detail I discovered supports my corruption theory, because Rambley may be battliing a glitch.