Cesti and Neki Assante were twin sisters. Orion Assante was their brother. They were rich aristocrats in the world of Grendel during the era of Pope Innocent XLII.
Orion was an activist trying to improve the life of everyday people, especially by taking down the corrupt Church. Neki and Cesti supported him but were not activists themselves. Instead they acted as his advisors and sounding board. He would often return to them for reflection during trying times. They were not in favor of his association with the Deva Princes. Cesti was known for her political advice.
When Orion brought them to the horrible bazaar that surrounded the Church, they realized just how bad things were, and saw an attack by Grendel firsthand.
Orion considered the twins to be smarter than himself. They were also more skilled in various areas, including fencing (their mother, whom they reminded Orion of, was an Olympic fencer). They also practiced gymnastics. They were very stubborn and headstrong. Cesti once stopping an uncle from tickling her by yanking on his mustache. She often wore earrings in the shape of a giant "A."
The siblings had an incestuous sexual relationship. In this world, this was a reaction to the plague of AIDS--families turned to each other for safe sex. However, the practice was largely gone by the time of Innocent XLII, and he tried to use their practice to turn public opinion against them. He was trying to do anything he could to get Orion to stop his investigation of the Church's finances. Orion ended up going underground, but the twins refused. C.O.P. tried to arrest them, but Cesti ran them off with a harsh verbal attack. Eventually they gave in to Orion's repeated entreaties, and agreed to join him in exile. However, when they left, C.O.P. chased them. They fired back, but in their haste crashed into a trash truck and died. Their death left Orion distraught and without an anchor in the world.