Fuuma goes to Kamui, almost nightly. The end of the world keeps getting closer and one of them will die. Both of them might die.
Fuuma wonders, briefly, what that would do. Would the world end, or be saved? He imagines it being plunged into some sort of abyss, send the entire world to purgatory for eternity.
Somehow, that seems even better than destroying humanity. They probably deserve it anyway.
But it matters less to him, the closer the day comes. He keeps remembering reasons humanity isn't all bad, things worth saving. He's trying his best not to care, but it all comes back to one thing. One person. Kamui.
Fuuma's stopped looking at people's Wishes. It's too ironic, knowing the hearts of everyone in the world except himself.
Fuuma's life is built around Kamui. First as Monou Fuuma, then later as the "Dark Kamui," everything he's ever done has been with Kamui in mind.
Kamui, for his part seems to be growing angrier with each passing night, at fate, at life-at humanity.
Fate chose badly, in this pair of predestined. It doesn't matter which one of them dies, the world will still be destroyed. They are both Dark Kamuis.