There is an odd, hanging pause between Irahl disentangling himself from his own mental drama long enough to process what Vincent is saying, play it back through his head a couple of times, and then turn again to send a rather cryptic look over toward Robin.

"...Is he."

It's cryptic in that it's a bit loaded, and it's loaded with so many different things that it's too much to convey briefly.

Robin knows what most of those facets are, and this fact is more or less what that look is all about. Maybe Irahl is finally becoming aware of their surroundings again, because there are many things that he could say right there, in that moment, but he chooses not to. Either that, or he's morbidly curious about how Robin would summarize to Vincent how they know each other, if he would even say anything at all.

Either way, Irahl only replies with a detached sort of, "...Funny."