In his first appearence in Identity Crisis Part One, Cyrus betrayed Bob and Dot by taking all Personal ID codes of an entire sector and brought them to Megabyte. In gratitude to Cyrus, Megabyte made him a lieutenant in his viral force.When Dot dicovered what Cyrus had done, she managed to get the PIDs back from Megabyte and thanked Cyrus for helping her...right in front of the angry virus; Cyrus was made into a leg polisher binome.
For along time, we heard nothing of Cyrus, thinking that he got what he deserved and that was that. But suddenly, in Season 3, Megabyte gives Cyrus a job of ruining Guardian Enzo Matrix's image in the eye of the citizens of Mainframe.
While leading a angry mob against Enzo, the entire group gets trapped in a game cube. After having Enzo save his life, and not wanting to be nullified, Cyrus helps the young Guardian defeat the game and is proclaimed a hero. When Megabyte discovers this, he is enraged and orders Cyrus' deletion.
Hack and Slash while fullfilling Megabyte's orders, get a sudden rush of conscience and can't complete the task, which results in Cyrus' escape.
At the system restart, the Norton Anti-Virus rids the system of anything viral, except Hexadecimal. Cyrus was released from Megabyte forever and even danced in the Mainframe Stroling Players Season 3 summary at the end of the show!