What term describes a person intimately involved with the plot and development of a novel?

The correct term that describes a person intimately involved with the plot and development of a novel is "character." Characters are the individuals that populate a story, driving the plot forward through their actions, decisions, and interactions with one another. They are essential for developing themes and evoking emotional responses from readers. Characters can be complex and can change or grow throughout the narrative, contributing significantly to the depth and richness of the storytelling.

In contrast, the narrator is a voice that tells the story and may or may not be a part of the plot. The protagonist is the main character around whom the story revolves, while the antagonist is typically the character in opposition to the protagonist. Both the protagonist and antagonist are types of characters but do not encompass all individuals within the narrative. Therefore, "character" is the most encompassing term that captures all individuals involved in the plot and development of a novel.