Given that the chair appears empty, and is also empty in the chapter cover page, I think that it's just shown because:
a) It emphasizes how weirdly spartan Tony's home is, or
b) It will turn out to be significant for some other reason later, e.g. the chair is facing out that window so that Tony can keep an eye on some specific building, person, or landmark.
I also think that Annie gave Rey to Kat intentionally, based on her reaction to her dad. This was the one thing that Tony asked that I could see Annie resisting, and given that Annie kept the walkie-talkie secret and the break-in plan secret, Kat is the one person who has been able to talk Annie into keeping secrets from her dad "just in case". But it looks like Annie did it at the last minute when Kat wasn't around to give any commands, or at least not with enough time to come up with a plan. Otherwise, Kat could have asked Rey to sneak out and meet her, and she wouldn't have had to teleport anywhere to find him.
It doesn't look like Rey is restrained, either physically or with Anja and Don's symbol, and if he knew that he was supposed to sneak out, he could have done so the very next time that Tony left to teach class. So presumably Rey's just staying put to avoid giving anything away, until someone finds him and tells him what's going on. Maybe Kat is going to ask Rey to run away while Tony and Annie are at dinner at Kat's place; this would give Annie and Kat a solid alibi, so that neither of them can be held accountable for having stolen Rey. However, this would force Kat to hide him somewhere else, if she doesn't want to get herself or Annie in trouble.
Based on what little we know about how Renard is bound, it seems that he can be transferred, but he can't be stolen because that would void his "contract of ownership". So if Tony's putting pressure on Annie counts as "theft", we would expect him to be freed, not given to Kat. At least that's what Jimmy Jims suggests:
www.gunnerkrigg.com/?p=161If theft didn't break the contract, or if Annie failed to transfer ownership correctly, we would expect Annie herself to still have ownership. Having it switch to some third party makes no sense.
It also seems that Annie has to be pretty explicit in order to give Renard away. She told Rey that she'd let him go if he wanted, but just making that offer didn't free him immediately. When Tony asks for control of Reynardine, she says "Okay", but that agreement doesn't transfer him. She said that she mentioned her intention to give him to her dad, and Rey complained, but she still compelled him to be silent after that, so that expression of her future intention directly to Rey didn't transfer him.
So if Annie unintentionally gave him away, it seems like it would have to have been due to extremely lucky vague phrasing on her part. E.g. if years ago she said "if anything ever happens to me, or I'm separated from you, Kat is your new owner", and then when her dad shows up, she hands him over and says something like "I'm giving you up now. You have to obey your new owner." But that really seems like a stretch. Alternatively, if being temporarily incapacitated was enough to transfer ownership, and if something as mild as being under her Tony's thumb counts as incapacitation, and if there's a long-standing agreement that the next owner would be Kat, that could theoretically do it. But that's an even bigger stretch to me, and in that case, we would expect that Kat would have already become the new owner during Divine. Yet Rey still has Annie's symbol in Divine (assuming that that part is real rather than a dream), and if there's a transfer, it's a pretty big plot point to have never mentioned.
Furthermore, Hetty's contract was passed down through a diary that neither she nor her new owner even knew about at the time, but the contract still bound her regardless. This implies that Reynardine can't just decide to interpret an ambiguous command to mean that he belongs to Kat rather than to Tony. It's entirely about some abstract concept of "rightful ownership" (whatever that means, in a system that's basically etherically-enforced slavery). Rey's intentions and beliefs appear completely irrelevant.
There are three other things that seem *technically* possible, but even more unlikely:
1) Tony's actions count as "theft" and break the contract of ownership, freeing Rey. But Rey doesn't want to be freed because he sees his contract as a form of penance, and because the Court would try to recapture him if he were a free agent, forcing him to fight or flee the Court. So even though he's effectively free, Rey somehow gives himself to Kat as a solution.
2) Tony could have the same symbol as Kat ("the mark of the creator"). But the Seraph robots are the only ones who seem to know the symbol, and Tony has no special connection to the Court robots that we know of. Kat is the only one who has *ever* been shown with the symbol, so far as I can find. Even Diego is only vaguely implied to be associated with it due to being the Court robots' creator, but it's never shown with him, leaving open the possibility that it wasn't actually *his* symbol in the way that it is Kat's symbol (e.g. maybe it's just a symbol he liked, or which had special significance in some of his diagrams).
The ROTD knows the Gillitie medium symbol, which is presumably held by only one person at a time. In fact it seems possible that only Ysengrin and Annie have ever held that position, in which case the ROTD only knows about it through Court ghosts who have seen it, or, less likely, due to Ysengrin himself having visited the ROTD. So the ROTD seems like it would have to be very on top of things to recognize that symbol, yet they still don't know the mark of the creator, which suggests that it's *really* rare, which in turn makes it even more unlikely that two people at the Court both have it at the same time.
3) Technically, it is possible that Tony had control of Rey, but then gave him to Kat, either deliberately or unintentionally. It makes no sense that he would do it deliberately, especially given that he bothered to ask for Rey in the first place, then to ask Annie why Rey didn't follow his commands. It's not clear what he possibly could have said to make the transfer unintentionally.
but I can also see the husky resemblance!
