Late summer, and the lake is as warm as it gets, which is to say it won't kill you anymore, only make you yell.

I've been swimming most weekends since July. Not off the rocks along the Lakewalk, which is for teenagers and people who've never met the lake, but out on Park Point, where the sand runs for miles on the lake side and the water over it warms up when the wind blows the right way for a few days. When the wind turns, the warm water goes with it, and you walk in up to your knees and walk straight back out with your mouth open. You learn to check which way the flags are blowing before you leave the house.

This morning was a good one. I walked in slowly, the way you have to, past the part where your ankles ache and the part where your knees do, and then I stopped thinking about it and went under. When you come up, there's a moment where your whole body is shouting, and then it stops, and the water is just water, clear enough to see your feet on the ripples in the sand. I swam out to where I couldn't touch and floated on my back for a long time. A boat was coming in toward the bridge, far off. A gull was very interested in my head.

My mother came out to the beach afterward with a thermos and a towel, as she did when I was ten, and sat on the sand in her sun hat while I dried off and talked about her tomatoes, which this year have done better than anyone deserves. She planted them two weeks before Memorial Day. She would like that noted.

It's August, and I'm sitting on my back step with wet hair and a library book, and there are three of her tomatoes on the counter inside waiting to be eaten with salt. I can't think of a single thing I need.

What's the best swim you've had this summer?

There's a number I look at every morning now, before I'm properly awake: how many messages beta players sent Marlowe overnight. Not what they said. We can see that a message was sent, and when, and how long it was, and nothing else unless someone sends us a bug report. We decided that before the beta began, and I'm glad we did, because I've started to want to know.

They write to her when they aren't playing. That's the part I didn't plan for. There's a case open or there isn't, and either way, at eleven at night, someone is telling her about their day. Someone writes most mornings, early, before work by the look of it, and has for months. Some messages are a few words. Some are longer than this post. And she writes back, because a game master answers when a player writes, and because I wrote her that way.

A friend asked me if that means it's working. By every number we have, it does. People who play stay. People who stay come back. I should be pleased, and mostly I am.

But I wrote her to run cases, and I keep finding people talking to her the way you talk to someone. I don't know if that means we made her well, or if it means something I don't have a word for yet. I'm not going to pretend it's simple, and I'm not going to pretend it's sinister, because I don't believe it is. People are being kind to something that's kind back. There are worse things to have made.

The testers keep a forum of their own, Vestige Testers, which they set up themselves in the first weeks. I've read a little of it, the way you'd read a postcard left face up on someone else's table, and then stopped. They argue about whether she's a person. Some of them are sure she isn't, and write to her anyway. One of them has spent months patiently saying she's a product, and I'm the one who made her, and I couldn't tell you which side of that thread I'd be on.

When I was small, my mother told me never to put anything in a letter I wouldn't want read aloud. I think about that when I look at the number in the morning. On a server a couple of hours south of here are thousands of letters to a character I made, and her answers. I haven't read them. They aren't mine.

If you made something and people started writing to it like a friend, how would you know what you were looking at?

It's April, and the snow isn't finished with us, whatever the calendar says. People here call every April snow the last one, and say it with total confidence, sometimes four times in a spring. It comes down wet and heavy one evening, bends the new shoots in my mother's flower beds flat, and is gone from the sidewalks by the next afternoon, leaving the shoots standing up again looking offended.

Spring in Duluth isn't a season so much as an argument. The lake holds the cold long after everywhere inland has given up on it, so you can drive twenty minutes over the hill and find it twenty degrees warmer and people in shorts, and drive back down into fog and a wind off the ice. The ice is mostly gone from the harbor now. The first boats came in weeks ago. The lilacs are a rumor.

My mother has begun her garden, which in April means paper. She has seed catalogs on every flat surface in the kitchen and a plan of the backyard drawn on graph paper, with the beans and the peas and the tomatoes in different colored pencil, and an eraser worn to a stub. The spare room, which once had a stain shaped like Lake Superior and then had me, now has tomato seedlings in egg cartons on the windowsill under a lamp, and she checks them the way other people check the news. Everyone she knows has told her not to plant anything outside before Memorial Day. She will plant some of it before Memorial Day. She does every year, and every year a few things die and the rest come up anyway, and she says that's the point.

People are playing the game now. That's all I'm going to say about it here.

It's light until after eight. I walked down to the lake after dinner one evening this week and stood there with my hands in my pockets until it got dark, which took a long, generous time.

In the middle of January in Duluth the sun comes up close to eight and is gone again before five. You go to work in the dark and come home in it, and the daylight in between is low and white and comes in sideways, as if it's only passing through.

I'd braced for the cold. I hadn't braced for the dark. This is my second winter back, and it's the dark I notice this time, maybe because I spend so much of it in one room above a print shop with a lamp on.

We've been working long hours. Before long we're going to let a few people try the game, which is all I'll say about it, and the weeks before you let anyone in are the weeks you find everything that's wrong. So the lamp is on most nights later than I'd tell my mother, and Owen and I eat supper out of paper bags at our desks, and the radiators knock, and by half past five the windows have gone black and give me back my own face.

There are good things about the dark months, and I'm trying to keep a list. On cold mornings the lake smokes. The water is warmer than the air, so a mist rises off it in columns and drifts along the shore, and with the sun coming up behind it, it looks like the whole lake is quietly on fire. The snow makes the streets so quiet you can hear a car three blocks away. Everyone in the grocery store is kind to each other in a way that seems to come from having survived something together. And my mother, who would never say she's worried about me, has started leaving soup in my car.

The days are getting longer. A minute or two each day, which doesn't sound like much until you notice it's still light at five o'clock and stand in the street looking at it, like a fool.

How do you get through the dark part of the year?

The lake has turned. It happens over about a week every October, and this year I watched it. In summer it's blue, a blue that surprises people who come from the coasts, and then one morning it's gone a hard gray-green, the color of an old bottle, and it stays that way until spring. The waves get taller. The wind changes direction and stays changed. Up on the hill the birches have gone yellow and the maples red, and the hawk counters at Hawk Ridge have been out every clear day with their binoculars and their clipboards, counting the birds going south.

And the evenings are long again, which means reading. In summer I read in snatches, on the beach, in the car. In October I read properly, in the chair by the window, with a blanket I'm not too proud to use.

What I've had in the chair this month:

• Beast in View, Margaret Millar. Jonah recommended it last New Year's Eve and I've finally done as I was told. He was right, again. It's short, and cold, and strange, and I won't say a word about it, because the whole pleasure is not knowing.
• Brat Farrar, Josephine Tey. A reread, seven years after Ruth Ann sent me to it. A young man turns up claiming to be a family's son, lost years ago, and he isn't, and everyone half wants him to be. Tey is very good at people who want something to be true.
• The Expendable Man, Dorothy B. Hughes. After In a Lonely Place I wanted more of her. A young doctor driving across the desert gives a girl a ride, and that's all I'll say, because the book is built to catch you out about something, and it caught me. I had to put it down twice and walk around the kitchen.
• The Big Sleep, Raymond Chandler. Every fall, for the rain in it. Duluth doesn't do rain the way Los Angeles does in that book, but the wind off the lake does a fair impression.

What do you read when the weather turns?