Traditionally as a guild member you’d just call the leader of a guild hall “Master”, as Kat and Halen are doing with Peck. As an outsider, though, Book isn’t so sure about that, so he refers to Halen as “Master”, too, since he’s basically the second in command in Serpent’s End (who would have thought? :O ).

Relettering is at page 120, and has thus entered chapter three (and is almost halfway done – hype!).

↓ Transcript
Katharina: And ... what do your feeling say about Master Peck? He IS acting strangely, isn't he?
Halen: I ... I wish you were wrong, but I'm starting to get worried. I'm just realizing HOW LITTLE I still know about his businesses. I'd never expect to know the city as good as he does, but I thought I had at least a ROUGH grasp of what was going on. After all, as his seneshal I should be the one handling the details while he tends to the big picture ... but it seems some things he just can't DELEGATE.
Halen: Or ... doesn't WANT to ... <he closes his eyes and sighs> He was right, sweetie. We really shouldn't talk about this HERE.
Katharina: ... yes. I'm sorry, Halen.
Katharina: So ... you're officially his SENESHAL? You never told me.
KAtharina: Ah, you know me, I don't care much about titles ... also "Seneshal" basically just means I am his personal assistant. Or SECRETARY, if you will.
Jester Book: <coming back into the dining room with a drink in one Hand and some books in the other> Sounds like we have something in common, Master Tuomi! I'm sorry for the delay ... I had to search my books. But good news: I found them! And I have your drink, Master Tuomi, so ... shall we begin right away?
Halen: With pleasure, Mister Book. And thank you for the drink with that ADORABLE little umbrella in it.
Jester Book: I hoped you'd like it!