Igret

Igret (also known as Agrat Bat Mahlat) is one of the four succubus queens. She makes her appearance in the Euryale Succubus Trilogy in Euryale's Gambit in the Cathedral. She handily defeats Euryale and drains her of all lust energy. She mocks Euryale's lack of memory and questions why Euryale is on the mission to prevent the US civil war when she had been cursed with apathy which had lasted for hundreds of years without issue.

Igret is one of a few succubi who is able to make use of lust energy and chaos energy. Being able to make use of both makes her extremely powerful.

Euryale's Gambit
During Euryale's Gambit, Igret has partnered with a mortal known as "The Master" to drive the agenda of the Demon Lords. The demons are using the practice of slavery to gain massive amounts of chaos energy from the resulting suffering. They are also actively engaged in creating war, which would result in much more chaos energy. With this energy, the demons plan on finally defeating the remaining forces of the plane of Heaven and occupy all three planes. Igret appears to be helping the demons by using her powers of suggestion to gain religious and political support for slavery and the war.