Atraxa sends Ixhel to eliminate Geth. The lich's challenge to her obedience reaches a vulnerability she does not want to name. She kills him, but the victory leaves her wanting to preserve and transform rather than merely deliver a head.
Using recovered parts and some of her own wings, she makes Vishgraz. Atraxa condemns the creation and insists that Ixhel herself is only a weapon. The desire to create has become disobedience because it was not ordered.
Ixhel takes Vishgraz away and lets him go instead of destroying him. She does not leave with him, and the account does not declare her converted to the resistance. Her act is smaller and more specific: a purpose-made soldier recognises a want of her own and defies the command to erase its result.