The unnamed character who looks back on his boyhood while narrating "The Sisters" is a figure of central importance to Dubliners as a whole. He is the first character in the book who the reader gets to know from the inside. He serves as a sort of template for the main characters of the two stories that follow (and perhaps that of "The Dead," as well), and he makes concrete the collection's major themes by embodying opposite qualities.
The boy is a natural character with which to begin a book because he possesses so many qualities attractive to readers. First, he is sensitive — sensitive enough to experience a wide range of feelings in spite of his tender age, including apparently contradictory combinations like fear and longing (at the end of the story's first paragraph), anger and puzzlement (while falling asleep), and, especially, "a sensation of freedom" in response to his mentor's passing that surprises him and us. "I found it strange," the narrator says, "that neither I nor the day seemed in a mourning mood."
Second, he is intelligent — and not merely in the conventional sense of the word. Sure, he is brainy enough to absorb much of the arcane information shared with him by the priest. (It makes sense that he has grown into the articulate storyteller who shares the tale of Father Flynn's influence upon him.) But the protagonist of "The Sisters" also possesses an intuitive understanding of how other human beings feel, think, and act — emotional intelligence, you might call it.
"I knew I was under observation so I continued eating as if the news had not interested me," he says of the difficult moments after he has received the bad news about his teacher. Moments later, he fills his mouth with food so as to avoid an outburst directed at Old Cotter. He is probably right in his analysis of the situation. Clearly, it is the wrong time to stick up for himself, or for Father Flynn. At the house of mourning, the boy carefully observes his surroundings and acts appropriately, entering on tiptoe, pretending to pray when that seems the thing to do, refusing crackers for fear of making too much noise eating them, and, most of all, remaining quiet. Even adults can often be insensitive to the mood of their environment. The boy, however, always interprets the emotional tone of his surroundings correctly.
It is no surprise that a boy so sensitive, so intelligent, would find himself somewhat alienated from others — cut off, fundamentally, from his family and peers. He appears to lack altogether a connection with his uncle, much less Old Cotter, and it is said that he rarely plays "with young lads of his own age." Even when he is in the company of his aunt and the priest's sisters near story's end, the reader's main sense of the boy is that he is alone.
Finally, though the main character of "The Sisters" is no more in charge of his own fate than most children, he has an independent spirit and a desire to discover the true nature of things that cause him to search beyond the boundaries of convention. He quests, as far as he is capable of doing so, for that which he does not yet know. It is this characteristic that presumably brought him to the priest in the first place, and leads him to the house of the dead man and finally to Father Flynn's open casket. It is also this active, seeking quality in the boy that makes him most appealing to us.
In the unnamed boy at the center of "The Sisters," James Joyce found a prototype to which he would return in at least two other stories, if not three. Thus, the boys featured in "An Encounter" and "Araby" share fundamental characteristics of personality with the protagonist of "The Sisters," including the aforementioned sensitivity, intelligence, alienation, and questing nature. In Gabriel Conroy (the protagonist of "The Dead") Joyce introduces what seems to be a variation on this prototype: the unnamed boy grown up, married, and with children of his own.
Joyce also illustrates the major themes of Dubliners by contrast, showing their opposites in the unnamed heroes of the book's first three stories. Paralysis is countered by movement, as all three boys take little journeys — the first boy to the priest's house, the second to the Pigeon House, and the third to Araby. Joyce underlines the corruption of his adult characters by means of the purity of youth: When their stories commence, the three boys are untouched by death, sex, and the pain of love, respectively. Finally, though surrounded by the dead and dying, the three unnamed boys have by no means given up on life. On the contrary, as children, they are just beginning to experience the world and its wonders, and tend naively to welcome all that comes their way. In "The Sisters," "An Encounter," and "Araby," James Joyce offers the reader a first glimpse into the demoralizing world of Dublin and Dubliners. At the same time, he offers hope, in the form of his three unnamed protagonists. His own hope, perhaps, was that the reader would remember these boys during later, darker Dubliners encounters.