No. He didn't know. Truth be told, given his own past with Stregobor and their...tense exchange shortly before the dance, Geralt had given no thought to the idea of another who might draw Stregobor's attention. He assumed the Butcher of Blaviken making a scene would be plenty. Stegobor had never hidden his disdain after what happened with Renfri—nor had Geralt.

Istredd was merely an easy choice of partner. Yennefer had informed him Istredd was working with Triss, and Geralt also knew the mage would go along without question. They'd had some history, however brief.

"I was using myself." He cracks a crystal off the rock. "Stregobor was there in Blaviken. It was where I learnt he had a predilection for experimenting on young girls."

Istredd must know of the incident, historian that he is, but Stregobor had taken on a false name at the time. Hiding from Renfri. Unless he ever spoke of it to Istredd, Stregobor's true identity would've gone unrecorded. Those villagers hardly paid attention to the sorcerer in the tower, anyhow. The only story they would've told was the Witcher who murdered men on their doorstep.

It was personal for him, too. And he made the mistake of letting that cloud his judgment. He should've noticed Vilgefortz's involvement sooner.

"I didn't realize he held some importance to you. But you helped us, anyway."