Since 1983, Jon Fosse has published, by my count, twenty-seven plays, twenty novels and eight collections of poetry. In Norway, he is so celebrated that the king has granted him permanent use of the Grotten, an honorary residence reserved for writers and artists in the grounds of Oslo’s royal palace. Yet so far, his work has not made a great impact on the English-speaking world.

His newest work is a series of seven brief novellas about a painter called Asle. Widowed, he lives alone in the countryside and no longer drinks. In the nearest city lives another man called Asle, also a painter, and a divorced alcoholic. In the first two novellas, published in English as The Other Name: Septology I–II, the first Asle drives around and thinks about his paintings before finding his namesake passed out in the snow half-dead and taking him to a local clinic.

Slowly, it becomes clear that between these men there exists a strange fellowship of fate. They are not the same person but, as it happens, they have been friends for years. Asle is gripped by visions of his drunken double shaking and moaning on the sofa of his city apartment. He seems to have flashes of insight into the other Asle’s past. Some critics have used the word ‘doppelgänger’ to describe the second Asle, but this relationship is stranger and more spiritual than anything a single word can encapsulate.

Each numbered episode in the series begins with a variation on almost exactly the same phrase. I is Another begins: ‘And I see myself standing and looking at the picture with two lines, a purple line and a brown line, that cross in the middle.’ The two lines cross like the two men’s lives. Each novella consists of Asle’s internal monologue – a stream of prose in the first person, unbroken other than by question marks – and occasional lines of dialogue. The monologue breaks off unpunctuated at the end of each instalment, when Asle falls unconscious.

Fosse is known for his ‘slow prose’, which is marked by frequently repeated thoughts and phrases and a constant reiteration of ideas and anxieties. It can be maddening to read:

now Asleik asks me what the painting he wants is called and I think I remember, I’m not totally sure but I think it’s called Silent Boat, that’s something you might call a picture, I think, actually it’s an awful title, I don’t know what I could have been thinking calling it that, I think, and I say that I think the picture is called Silent Boat but he can just look for himself, I say

With few proper names and no clear sequence of events, the eye has a habit of losing its place (or flicking surreptitiously down the page). Fosse’s grey verbal palette would seem inimical to representing the visually attentive consciousness of a painter. Yet this technique allows Fosse to freight his story with a sorrow that is all the more painful for its constant proximity to the boredom and frustrations of real life.

In the two episodes published in The Other Name, this repetitious mundanity culminates in passages of radiant grief. The three episodes in I is Another are more of a mixed bag. If they answer certain questions about the mysterious relationship at the heart of the book, they also raise new ones. The three instalments pick up just where the last ones left off. They take place over a day and a half, a lot of which is spent driving. In these vacant periods, the narrative leaps suddenly back to Asle’s life as a young man and he sees himself forming a band, leaving school and taking his first steps as a painter. The transitions back in time are presented as sudden visions, beginning with ‘and I see’: ‘and I look at the white road and I see Asle standing in front of Mother and he’s thinking that he can’t stand going to that damn school anymore, the teachers are unbearable, why on earth should he keep going?’

In fact, they are introduced in a similar way to Asle’s vision of his namesake, currently in intensive care: ‘and I stare blankly straight ahead into empty space and nothingness and I see Asle lying there with lots of tubes connected to his body.’

The reader’s understanding of the relationship between the two Asles flexes and changes. With some of the story lines and scenes feeling slightly redundant – an argument about a band, a subplot about anxiety in the classroom – what the precise nature of the relationship actually is becomes the pressing question of the book. It remains unanswered when the fifth instalment ends, like its four predecessors, with Asle praying and counting the beads of his rosary, as Christmas draws closer. The novel’s epigraph, ‘Je est un autre’, is taken from Rimbaud; like the title, it suggests something irreducible about the link between these men’s lives. But something more than the inconclusive unease of I is Another is now demanded of the series’ end. It has been a strange, difficult and sometimes beautiful journey so far. In the final instalments, Fosse has promises to keep.