Azzy might have spent far less time with Barbara when compared to any of his friends but he trusted her as much as he trusts Gideon or Claire. It has never crossed his mind that she of all people would even think of betraying him.
As Azzy stared at her in a daze, the Reaper's voice then echoed in his head, "What will you do now, Azrael? She has turned against you."
"No, I believe that it's just the work of Protos energy." Azzy refused to accept that she chose to harm him on her own because if it is that way, then, he will be forced to kill her.
The fact that she's currently bathing in Protos energy only helped his theory. He attempted to converse with her in his own style, "Barbara, you don't know what you are doing right now. These actions of yours will have disastrous consequences."