As a younger man I went through a big Trevanian phase. I thought The Eiger Sanction and The Loo Sanction were great and I think I read Shibumi a several times. I didn't realize it at the time but those books were really intended to be satires or parodies of the genres that they were written in. I took them quite seriously though. The Main had a much different tone though. Trevanian seems almost reverential about lost Montreal in this book - the immigrants, the cops and the rough underbelly of St. Laurent.
The novel is all that much more enjoyable because of it's slow pacing and deep character development. It is a shame that he never wrote more books in this setting.
In an interview Trevanian says, "...I had brewing...a cycle of five novels set in Montreal (home of the French/Indian side of my family). These novels were to deal with various segments of that fascinating, multi-cultural world, and each of these novels would be written in a different genre: a love story, a story of revenge, a roman policier, a tale of struggle to success at the cost of humanity, a mystery story. Many of the characters would be recurring — a lead in one novel turning up as a walk-on in another. And each of the novels were to be named for the section of the city in which the principal events occurred."