A prisoner here? Well. Benedict's mentor had been sent off to Skyhold before Byerly had arrived here, so By doesn't know much about the man. For example, does he have a son who's prone to being bullied by little girls? Unknown, but not impossible. And: a Vint, familiar with Artemaeus, a former prisoner? There aren't too many people who fit that profile.

Still, Byerly isn't completely sure that this is Vedici's son, and he doesn't want to ask directly (so as to maintain an air of omniscience), and he doesn't want to say outright he's not here (in case he's wrong about the lad's identity, which will, again, undermine his air of omniscience).

So instead, he says, "Ah," knowingly, and then asks, archly, "Seeking to join him? Fight at his side?"