Martyrdom at Nicomedia
The account of these three martyrs is bound to that of the Great Martyr George, whose endurance under torture drew a number of bystanders to faith in Christ. The synaxarion places Isaac, Apollos, and Quadratus among the court officials at Nicomedia who, having seen George's confession, abandoned their pagan service and openly professed Christianity, rebuking the emperor to his face.
For this confession they were condemned. The tradition distinguishes the manner of each death: Quadratus was beheaded with a sword, while Apollos and Isaac died of hunger in prison. The three are kept together in one commemoration on April 21.