It's a complicated story, perhaps, but not a difficult one. At least, war, hatred, and vengeance are all things that Rezo himself had witnessed in his own world, not just Esthere.

(Abulah's plan sounds hypocritical to Rezo's ears, but that's obviously not the important part.)

It's mostly the telepathic elements that give Rezo pause, although even then he gets the concept well enough. The idea of someone being able to reach into your mind, to overwrite your emotions and memories with their own is, well...

Rezo is quiet for a moment after Atom's finished, mulling the information over. "I see. So in the end, you were able to understand one another's feelings?" Or at least, Atom had come to understand Sahad.