- "The Templars are crucial and cynical – I can tell. "
- ―Antonis one becoming an Assassin
As he saw the rise of power of the Templar Hacer Stavros, Antonis served as a scientist and blackmailer. For Hacer, Antonis was nothing but a Maroon. Antonis did errands for the Templar Order, being counted as a man-to-be-there – meaning he would always be disposable for the Templars. All of this made him angry: he felt that he could do much more than studying Pieces of Eden they already knew about: the Apples and Staves.
After the fall of Hacer Stavros, the Greek Assassins Maria Nomiki and Sofia Sanna established an Assassin guild, and was pointed out to leaders of the guild – and the growing colony of the Greek Brotherhood. Three Assassins that was sent to Cyprus in order to support the two lovers; Antonis took this chance to leave the Templar Order and offer his abilities for the Assassin Order.
Maria and Sofia argued why he should and should not be a part of the Order, so decided to test him: kill the Turkish merchant Hüseyin Teke – a Templar ally. Antonis would have no problems in doing so. After removing him from the docks of Kyrenia, the lovers sent him to kill Arsla Teke, Hüseyin's brother. After doing so, the Ottoman Templar Orhan Demir began to hun Antonis. He sent one of the most skilled Templar-killers, Fevzi Burakgazi, to kill Antonis. After surviving two meetings with the Templar – killing Fevzi during the second attempt – Antonis was accepted as a part of the Assassin Order.
At some point after the fall of the last Templar of Cyprus, the Assassins discovered the Sense of Eden, a necklace left behind of the First Civilization. It was brought to Kyrenia for further study by a Antonis. The man soon discovered its abilities, and felt stunned when he wrote them down.
During a Templar-campaign in 1736 lead by Constant Lavoie and Philippe-Hugues Bertas – and supported by Orhan Demir – the Greek Assassins had to flee to Kyrenia. In Kyrenia, the Brotherhood was in full disarray. After some negotiating between themselves, they agreed on that Maria Nomiki's son, Khayri, was to bring the Piece of Eden out of the city while the Assassins would keep the Templars busy. While preforming the leap of faith – in order to initiate the attack – Stylianos was hit by a bullet; disturbing the acrobatic stunt, Stylianos was killed by the impact when he hit the ground.
Short time after Stylianos' death, Antonis met with the Megalos-siblings. They found some of the mercenaries and they fought their way to an artillery. At the place, Constant, Philippe-Hugues and Orhan was to be located. The Assassins attacked. Orhan quickly ordered the soldiers to fire the cannons. The cannonballs flew through the air and destroyed the tower of the Assassins. As a signal, several snipers come out in the windows and pointed their guns at the Assassins – the mercenaries was either killed, busy fighting other or supporting in the Assassins' attack. Several of the Templars' soldiers came up from the sewers and surprised all of the Assassins and their acolytes.
Craving to know where he could locate the Templars' library and the Sense of Eden, Constant asked Maria for the answers. He killed each of the remaining Assassins, one by one – starting with Antonis.