As a note on Demon Ai, she's what I'd describe as a shallow charicature of Ai. With little to no personality to draw from, the demon fragments that escaped from Yuri's camera, well. Besides what of Ai that hanged on, she's essentially all the banal and shallow assumptions would make of Ai. She's much looser, more amoral, far less guilty about her nature.

She also lacks a bunch of Ai's more deeper details. She doesn't like birds, Human Ai probably enjoys softer more relaxing music while her Demon counterpart prefers more bombastic and organ-y music. Her cooking is also spicier than Ai's. ... And probably doesn't dislike Yuri as much as Human Ai would.

Ironically, she might of developed a more extensively separate personality from Ai if Yuri wasn't a cowardly little weasel.