The unnamed narrator of The Moon and Sixpence is a writer, and he is also an aficionado of art. He is likely based on W. Somerset Maugham, the author.

One very powerful connection the narrator has to Strickland is through Strickland's wife, who the narrator meets first and becomes attached to. Although their friendship is described in platonic terms, it is clear that the narrator finds her appealing:

During the summer I met Mrs. Strickland not infrequently. I went now and then to pleasant little luncheons at her flat, and to rather more formidable tea parties. We took a fancy to one another. I was very young, and perhaps she liked the idea of guiding my virgin steps on the hard road of letters....
(Maugham, The Moon and Sixpence, Google Books)

Use of the term "virgin" is perhaps more salacious today than it was in 1919. Still, both being writers, the narrator is connected with her, and it is only later that he becomes interested in Strickland, who he sees at first as "...a good, dull, honest, plain man."

After Strickland's strange decision to abandon his life and live in poverty to pursue his art, Mrs. Strickland asks the narrator to go and bring him back, or at least see him, and he finds Strickland utterly unconcerned about the well-being of anyone else. Throughout, the narrator is fascinated by Strickland's motives, and particularly his focus on art above all else; he has no sense of responsibility, nor does he care when a model commits suicide because of him. He is now entirely a creature of his art, and the narrator feels compelled to tell his story.