Desdemona is a power sorceress who basically took over the 9th circle of Hell and now runs the Satan Service company, granting requests for poor unfortunate souls in exchange for those very souls when they inevitably croak, most oftn by her hand or the hubris of their requests. So she's basically the new female satan.
A demoness from the innermost circle of Hell. She and ??? seem to know each other, though their relationship remains unclear.