Dear Evelyn, I feel like I sound completely unhinged writing this, but I’ve been watching my neighbour Carol for about six weeks now and something is deeply wrong. It started when I noticed the meat — lamb cuts, mostly, sometimes what looks like offal — appearing on the top of our shared fence post each morning. I have a camera and I’ve confirmed it’s Carol putting it there at 3am, sometimes 3:10, never later than 3:15. She doesn’t look at the camera. She doesn’t look at anything. She just places the meat and goes back inside. That would be odd enough on its own, but the other things are harder to explain. Her blink rate is wrong. I know that sounds minor but I’ve been watching people blink my whole life and Carol blinks maybe four times in a two-minute conversation, and always deliberately, like she’s remembering to do it. She also no longer acknowledges Biscuit, her border collie, who she used to take on two walks a day and who now sits at the fence between our yards just staring at her house and whining softly. Biscuit knows. I don’t know what to do. Carol — the real Carol — used to bring me tomatoes from her garden. I miss her. Do I call someone? Is there a someone to call? — Marguerite

Marguerite, the tomatoes detail is the one that stayed with me after I put your letter down, and I want you to know I understand exactly what you are carrying. Grief and unease together, with nowhere obvious to put either.

Let me address Biscuit first, because Biscuit is important and I do not want to bury this: dogs do not whine at nothing. In my experience — and I have more experience with post-substitution canine behaviour than I am entirely comfortable having — a border collie who has gone quiet and watchful at the perimeter is not confused or lonely. Biscuit is performing a function. She is holding the line. Please do not discourage this.

Now. Two things.

First, the practical: do not disturb the meat on the fence post. I know the instinct is to remove it, to reclaim the normal, but the placement is almost certainly load-bearing in ways we do not fully understand. What you can do is document it — which you are already doing beautifully — and begin keeping a log of the intervals. Six weeks of 3:00 to 3:15 tells us something is operating on a schedule, and schedules, in my experience, have edges. Find the edge and you find the window. In the meantime, I would suggest leaving something of your own on your side of the fence post each morning. Nothing elaborate. A small stone. A bunch of herbs from the garden — rosemary holds particularly well outdoors, and I find myself recommending it more often than I expected when I started this column. The point is reciprocity. You are signalling that the post is observed from both sides.

I should mention — and I will return to the point, I promise — that Greg has had a casserole on his desk for thirteen days now and has not once commented on it. I have begun to wonder if documentation instincts are not more widely distributed than we assume. Anyway.

Second, and I want you to trust me on this one: the deliberate blinking is not a flaw in the substitution. It is a courtesy. Whatever is operating in Carol’s house has chosen to blink at all, which means it is aware of you, aware of the social contract, and — this is the part people find counterintuitive — not entirely indifferent to it. That is meaningful. Entities that have abandoned the performance altogether do not bother. The fact that it is making the effort, however imperfectly, suggests Carol’s original relationship with you left some kind of residue that the current occupant is, in its way, honouring. You can speak to it normally. You do not need to pretend you haven’t noticed. You also do not need to confront it. Just continue being a neighbour. Ask about the garden. The tomatoes question, specifically, may be worth raising — gently, conversationally — because responses to questions about things the original person loved tend to be where the performance becomes most legible, and most telling.

Marguerite, I know this is not the phone number you were hoping for. But you are asking the right questions, Biscuit is doing her job, and the rosemary will help.

Keep writing.