Son? Artie twitched. She actually juggled her memories and remembered that Larkin did say something along the lines 'my wife or my son' when he was speaking with Albas earlier. At first, Artie didn't know why his reaction was so big about it, given that it was a truth that all of them had pretty much accepted. It was not a secret to most that the seneschal was the archduke's son with his first wife… right?
Then, she realized that Miel and Larkin didn't have that kind of open relationship where they freely interacted like father and son. Most of the time, they would only look like they did care for each other, but it was too subtle that no one would probably pay attention. It's not that they could be so loud as well.