Born to an Egyptian farmer and a Greek woman, Theodoros' father worked in a fig farm in the Faiyum for a living. During the reign of Ptolemy XIII, Derratos, a general under Ptolemy, taxed the Egyptians in the Faiyum region, including Theodoros' father. One season, his father struggled to pay his taxes due to poor harvest. As a result, Theodoros' father was hanged by Derratos on a fig tree and left there to be picked at by wild animals in the region. After burying his father, Theodoros joined a group of rebels in Saqqara Nome and eventually became one of their leaders, dedicating his efforts to hunting down Derratos and avenging his father.
In 48 BCE, Theodoros discovered Derratos' whereabouts and led his men in an attack. However, due to the overwhelming number of men Derratos had, the rebels were forced to flee and Theodoros was captured by a scouting convoy. However, this was all according to Theodoros' plan, for he was actually leading the Ptolemies into a trap. Along the main route to the Faiyum, the rebels ambushed the convoy with the aid of the Medjay Bayek of Siwa. Theodoros expressed his gratitude to Bayek and invited him to join him in their rebel hideout in Bakchias to regroup before hunting down Derratos.
Upon arrival in Bakchias, Theodoros and his men came under attack by the Ptolemies though they were quickly dispatched. Due to his attack on Derratos' camp previously, Derratos left his camp and went on the move, thus preventing Theodoros from achieving his goal again. As such, Theodoros came up with a plan to learn about Derratos' whereabouts, enlisting Bayek's help to locate Derratos' scribe in Karanis and interrogate him for information. Bayek did so, travelling to Karanis, eliminating the guards and taking the scribe back to Bakchias. From the scribe, Theodoros learned of Derratos' scheduled arrival in the Beached Trireme Camp and directed Bayek to meet his men in the hills north of the camp to be briefed.
A few nights later, Theodoros arrived and briefed his men about the attack. Together with Bayek, they charged down the hills and raided the camp. Derratos himself was captured and his men were slaughtered. Theodoros reminded Derratos about the killing of his father by shoving down a fig into his mouth before dousing him with a jar of oil. As Derratos tried to flee, Theodoros shot him with a flaming arrow, thus killing him and avenging his father's death.