Istredd tells himself to stay calm, he doesn't know her well enough to be judgmental about resisting destiny and all that. He's never been part of any kind of destiny. Now he feels like he's accidentally stumbling into the middle of it with no real idea for why.

"Whether you like it or not, it's true. You're the only person who can destroy or use monoliths. What would you call that? Ordinary?"

It was much easier to see her as a name on a page, a curiosity, someone with incredible power born to be a symbolic leader. Now that she's flesh and blood in front of him, and he interacted with her before this became real, it is much more confusing.

"Geralt doesn't know that I know, we didn't discuss that, I assumed you were back home so it wasn't necessary to bring up." He doesn't know why he assumed that, he knows Yennefer and Geralt are here, why not the Princess? Well, because again, she seemed so far away.

"I have a lot of questions for you, but I assume you're in no mood."