It is interesting to note that the narrator remains unnamed, even though the other characters have either names or nicknames. This makes the narrator a bit of an everyman, and allows the readers to see the story through his eyes. It also puts the narrator on the same level as Bartleby. The three other workers - Turkey, Nippers, and Ginger-Nut - all have character traits that indicate they have passions and lives outside of work. However, the focus of the plot is on Bartleby's inability to find a purpose in life, to find something he prefers to do. Work is all he is. Similarly, the narrator is only known to us as a lawyer, suggesting that he, too, has little life beyond work. This could be the reason he is so captivated by Bartleby, because he sees himself in this other man.
The narrator of this work is the unreliable lawyer. The lawyer admits in the work that he makes assumptions, so when we see other characters' actions, they are coming through his lense. This point of view increases the mystery of Bartleby's behavior.