It's not necessarily the Nexus he's most concerned for, if the Necrophos is anything like that title makes him suspect; there's a limit to the trouble the monk could cause here. But are also countless unguarded portals to worlds where he could potentially roam unchecked, and it's mainly due to the efforts of the Caelus brothers that the route to Tamriel isn't one of them.

Which is why, when that quiet invitation is issued, he looks up at Stratos again, hands stilling. "He... I think he was making me ill, or trying, the entire time we spoke."

He doesn't know it for sure, of course, but he didn't fell the slightest bit ill before encountering the mysterious monk. And there was the matter of the potion, too; it had been made correctly, he would lay money on that, so why hadn't it worked as it should have?