Mmm. [Reads something like mmhmm, and comes with a slow nod.] Well, if your world's been cut off from the other planes for a near eternity, it would make sense: demons have been locked in warring struggle for longer than all recorded history itself. They envy without end— desire dominon even amongst each other. Some mindless as a husk, others so cunning you'd find yourself caught within a blink.

With only one plane to contain them, and no master— perhaps even no will— well.

Focuses do narrow. And evolution is a wonder.