In the 440s BCE, after the girl was cast down from the top of Mount Taygetos by her adopted father Nikolaos, Ikaros was found – as a hatchling – by Kassandra. The eagle remained by her side as she fled from Sparta and ended up on Kephallonia. Forming a close bond, Ikaros often operated alongside Kassandra during her future career as a famed misthios to the extent that her epithet was "Eagle Bearer". Due to their connection, many considered Ikaros to be "eagle of Zeus", as eagles were the sacred animals of the Greek god.
As the natural life expectancy of a Golden Eagle is 30 years, by 422 BCE Ikaros was nearing the end of his natural life. When Kassandra met Layla at the Gateway to the Lost City in 2018, she merely mentioned that Ikaros had long since passed away.
Ikaros' reconnaissance ability was of great help to Kassandra during her travels. In addition to this, Ikaros helped her also by attacking those who had targeted her, and by distracting Kassandra's human enemies at her bidding.