"The reception here has been different from all the other interactions I've had in this area and I'm not fully clear on why."

If you gave me more detail I could probably hazard a better guess but I would observe that the smartest thing to do about a problem is usually to make it someone else's problem.

"And you decided not to do that."

Maybe I'm not very smart. Or maybe I didn't have faith in any somebody elses.

"Or there's a catch."

I do not anticipate gaining anything more from this than a useful ally and some knowledge of what she is and where she comes from.

Sigh.

"Do I need to settle anything up right now?"

"I can schedule you for some patrols later that'll even us up."

"How do those work? In my case since I'd be alone and not engaging."

We have a map that's the route one can take to see every bit of every path in our territory. You walk it or fly it. If you see anyone heading towards us, you wait to see if they cross within the border; if anyone is already there, you go and get other guards and tell them where.

"Okay."

Patrols are irregular but any given spot should be seen at least twice an hour.

"Do you actually have incursions often enough that that makes sense?"

It's not that they're frequent, it's that they're potentially disastrous. Over a couple of winters, you will have a couple of dozen people wander through here - lost, malicious, curious, whatever - and if you don't know about them then your court accumulates entanglement and dies someday without any of you knowing it. 

"You can obviously sense some entanglement."

If you see a person you have perfect information about their status with respect to you and reasonably good information about their status with respect to anyone else around. If you never see them it is possible for them to be in your debt without knowing it; if I planted a rosebush halfway across the continent I wouldn't get informed whenever anyone picked a rose from it. 

"Huh."

If I wanted to take over a neighboring court, I'd send some people in between patrols, get them indebted, start causing misfortune, offer aid to cope with the misfortune once it became obvious, make the aid difficult to repay, and then eventually walk in and do whatever I wanted with everyone. 

I have never done this. But the only reason it'd be hard are the neighbors's patrols.

"- can courts as entities be in or owed debt?"

It's not actually meaningfully distinct from debts to the person controlling the court, in the sense that that person is subject to all the fortunes of the court and also can transfer between court and personal debts, but yes.

"You can transfer it too?"

If I owe you, and you owe my friend Leaf, and Leaf owes me, we can all sit down together and arrange to be even, if all the debts are the same size, or for the debts to be reduced by the size of the smallest one, in the more typical case.

"I guess that's better than not being able to do that."

Courts would probably be intractable if you couldn't do that.

"Or at least much more confusing."