Early in Oscar Wilde’s novella The Canterville Ghost, the Otis family is being shown through the estate of the Canterville family, a large, palatial home with a library befitting the aristocracic lineage of the Canterville family. That history, however, includes the murder of Lady Eleanor Canterville at the hands of her husband, the titular character who now haunts the estate. It is while touring the library that Mrs. Otis notices the bloodstain on the floor near the fireplace. Her discovery precipitates a series of actions and reactions that demonstrates the ghost of Sir Simon de Canterville’s appreciation for family history and the imperative of maintaining the home precisely as it existed upon his demise.

The Canterville Ghost is about the interactions between an American family lacking the history and eccentricities of the English and the ghost that haunts the house in which they are residing. It is from the stark contrast between the ghost’s “Old World” ways and the Otis family’s “New World” pragmatism that Wilde’s narrative derives its humor. The Canterville Ghost makes telling observations regarding the “old” and “new” worlds, and the bloodstain serves as one of the story’s main instruments with which the author illustrates those contrasts.

The bloodstain, as the elderly housekeeper Mrs. Umney states, was from the death of Lady Eleanor Canterville at the hands of her husband, Sir Simon, now a ghost condemned to haunt the structure. The bloodstain has since become a colorful feature of the home until the Otis family enters the picture. Ignoring Mrs. Umney’s observation that “the blood-stain has been much admired by tourists and others, and cannot be removed," the family immediately prepares to remove the blood from the floor using modern cleaning formulas. As the story continues, however, the bloodstain reappears every morning after being removed by the Otis’s, a fact eventually attributed to the ghost’s tenacity in preserving the bloodstain as a landmark. Indeed, undoing the Otis family’s repeated efforts at permanently removing the stain remains the ghost’s obsession, continuing his efforts even when feeling sick (“For some days after this he was extremely ill, and hardly stirred out of his room at all, except to keep the blood-stain in proper repair.”) As Wilde’s narrator points out, the ghost even targets Washington Otis for special treatment because of the latter’s role in continuously removing the new stains.

The reappearance of the “bloodstain" every morning, as the reader discovers, is the product of the ghost’s use of the Otis children’s paints to fabricate a new stain, which explains the stain’s evolving colors. Eventually, however, the ghost tires of this exercise, having succumbed to the children’s taunts and tricks:

“The next day the ghost was very weak and tired. The terrible excitement of the last four weeks was beginning to have its effect. His nerves were completely shattered, and he started at the slightest noise. For five days he kept his room, and at last made up his mind to give up the point of the blood-stain on the library floor. If the Otis family did not want it, they clearly did not deserve it. They were evidently people on a low, material plane of existence, and quite incapable of appreciating the symbolic value of sensuous phenomena.”

The ghost continues to repair the bloodstain because it is, to him and to the housekeeper, a part of the house’s character. Americans, the ghost concludes, lack the upper-class sensibilities of the English aristocracy. They are unrefined and undeserving of the heritage the bloodstain represents.

In Chapter One of "The Canterville Ghost," Mrs Umney informs the Otis family of the history of the famous bloodstain. It is the blood of Lady Eleanore de Canterville, who was murdered on "that very spot" by her husband, Sir Simon, in 1575. Later, in Chapter Five, the reader leans that Sir Simon murdered Eleanore because she was "very plain" and poor at housekeeping. She never starched his ruffs properly, for example, nor did she properly serve a buck that he had shot. 

Because of its personal history, Sir Simon, the ghost, goes to great pains to preserve his wife's bloodstain in the library. After Washington Otis removes it with Pinkerton's Stain Remover, the family finds that the bloodstain has reappeared every morning. Virginia Otis later learns (in Chapter Five) that the ghost stole her paints so that he could "furbish up" the stain each night. This also explains why the stain appears in different colours, including vermilion and emerald green. 

The bloodstain, then, is a physical reminder of Sir Simon's past crimes and of the house's murderous history. It also acts as a barrier to Sir Simon's eternal rest: the stain cannot be truly removed until the ghost repents of his sins and has left Canterville Chase.