"Yes, I know it very well," Sephiroth says.

He ponders. "It's difficult for me to imagine a world where there is no betrayal." And he nods. "I am not bitter, really.... I wonder if it was my fault, if I came across wrong or if he misread me. And as hurtful as what he did was, it unfortunately pales in comparison to what I did later to others."

He says this only because he doesn't want to appear as a guiltless victim of betrayal when in his mind he caused a far worse and unforgivable one.