Dr. Peter Venkman: What I'd really like to do is talk to Dana. Dana? It's Peter.
Dana Barrett: There is no Dana, there is only Zuul.
Dr. Peter Venkman: Oh, Zuulie, you nut, now c'mon. Just relax, c'mon. I want to talk to Dana. Dana, Dana. Can I talk to Dana?
Dana Barrett: [in an inhuman demonic voice] There is no Dana, only Zuul!
Dr. Peter Venkman: What a lovely singing voice you must have.
Zuul's responsibility is for communicating with Vape and registering the Bastion with Opsee.