The fourth floor of the library

You end up on the fourth floor by elimination, not by choice. The ground floor has the café and the talking that comes with it. The first floor belongs to the freshers, who revise in groups and think whispering solves it. The second has the printers, and printers have queues. That leaves the fourth, with the bound journals nobody has opened since everything went digital, and an old air conditioning unit laying down a flat hum over the rest.

There are eighteen desks. In revision week, fifteen are taken by nine in the evening.

You always sit at the last one on the right, against the window over the car park. It isn't superstition. It's the only desk with a working socket.

He sits at the third on the left. You noticed that on Monday. You noticed it again on Tuesday. By Wednesday you realised you were already noticing before you picked a desk, which is information about you and not about him.

He revises something with tables in it. You can see from a distance: loose sheets, columns, more red pen than can possibly be good news. In the gaps he doesn't reach for his phone. He looks at the wall for a minute, sometimes two, then goes back. You find that odd on Monday and rare by Wednesday, and after that you stop filing it.

Thursday, twenty to eleven.

The older collection is at the back of the floor, behind a glass door that doesn't lock. The lights in there run off a sensor. If nobody moves, they go out after ninety seconds.

You need a bound volume from 1998 that the university never scanned, aisle F, top shelf, and you are in trainers and still have to go up onto the first step of the metal kick stool, which creaks, and a creak in that silence sounds like furniture being dragged.

"Sorry."

You weren't talking to anyone in particular. But he is in aisle G, on the other side of the same run of shelving, and you only find out because he answers.

"There's nobody in here to bother."

You come down off the stool with the volume under your arm. The shelving is steel, open on both sides, and where you pulled the book out there is now an empty rectangle at chest height. Through the rectangle you can see his shirt. Grey, collar open, a pen mark on the pocket.

"Nineteen ninety-eight," he says. "Anything good happen in 1998?"

"There's a paper my supervisor cited and I suspect he never read."

He laughs. It's a low, held-in laugh, the laugh of somebody who has been shushed on this floor before.

The light goes out.

Ninety seconds is shorter than it sounds when you are reading an index.

Dark in there isn't full dark. Something comes in off the car park through the far window, grey, enough for you to see the shape of the shelving and not what's on it. The sensor is at the end of the aisle, facing the walkway. You had your back to it.

"If you walk to the middle it comes back on," he says.

"I know how it works."

"I know you know. I said it because I'm not going to walk."

You stay where you are. Not as a decision. You stay because deciding would mean admitting there is a decision in the room, and for now it can still be called a badly calibrated sensor.

The empty rectangle is still there in the shelving, at exactly chest height, and it is the only thing the two of you have in common. You think about that with a clarity that doesn't suit the hour.

"You sit at the third on the left," you say.

"And you're the last one by the window."

"Because of the socket."

"I know. I tested all of them in first year."

He talks slowly, in no hurry to fill a pause, and you notice you are doing the same. Nobody in the dark is trying to sound interesting. It's the most comfortable conversation you've had in three weeks.

His hand appears in the rectangle. It doesn't come further. It rests on the lip of the shelf, on his side, fingers crossing maybe two centimetres past the middle of the board onto yours.

You look at it long enough that it stops being a question.

Then you put the 1998 volume down on the bottom shelf, carefully, because a book going over in there would light up the whole floor.

What happens in the next twenty minutes happens in the dark and without noise, which are the two conditions the building imposes and neither of you chose.

The steel is cold against the back of your hand. The lip of the shelf leaves a mark. He works that out before you do and shifts how he's holding on, and it is the first thing he does for you that he didn't have to.

You learn that it is possible to laugh with no sound at all. That the sleeve of a grey shirt is thicker than it looks from across a room. That ninety seconds is an elastic unit: the light doesn't come back, and neither of you moves enough to bring it back, and you start to suspect the sensor is on your side.

At some point he says your name. You hadn't told him your name.

"It's on the front of your folder," he says, when you ask. "It's been there three weeks."

At twenty to twelve the security guard comes up. He knocks twice on the frame of the glass door without coming in and says they close at midnight, the way he says it every night, to a floor he assumes is empty.

The walkway light comes on when he passes his hand over the door sensor.

You are a metre apart, one on each side of the shelving, and the empty rectangle is still between you like a small window put in the wrong wall.

He has a red mark on his neck that is going to take about four hours to fade. You have shelf dust down the whole of your right sleeve.

"Are you coming Friday?" he asks.

"Friday I've got an exam."

"I know. I asked if you were coming."

You put the 1998 volume back on Friday morning, before the exam. Slid it into the right slot, pushed until it lined up with the others, and the rectangle went out of the shelving as though it had never been cut there.

The following Monday the third desk on the left had a girl in headphones at it.

You sat at yours, next to the socket, and at twenty to eleven you got up and walked to aisle F.

You didn't need anything from there.