The Grangerfords and Shepherdsons are aristocratic families that Huck and Jim encounter on their journey. Twain uses the families' decadence and wealth to explore class, and he also highlights the gaudiness and tackiness of the Grangerford house to mock American tastes and styles.
In an homage to a classic element of romantic literature, the families have been feuding for years, though no one can recall how or when the feud began. They are incredibly suspicious of one another and mistrustful of those around them. When Huck knocks on the door of the Grangerford house, the host demands to know if Huck is a Shepherdson and barely opens the door enough for Huck to enter, as if he expects the Shepherdsons to descend and attack at any moment. In the Grangerford house, we see the family develop in a way that contradicts their initial characterization as a violent, paranoid unit. Once they understand that Huck is not a Shepherdson, they take him in, feed him, and share family stories. Huck describes the host of the house as being "a gentleman all over; and so was his family." This contributes to the overarching theme of moral confusion; Huck routinely meets people who appear contradictory to him. In the case of the Grangerfords, they seem kind-hearted, but they also allow their lives and behaviors to be dictated by a petty and violent feud.
Twain uses the families to connect feuds with a profound sense of immaturity and therefore comment on the absurdity of adult society. Adults in Huck's life such as the Widow Douglas and Miss Watson urge Huck toward the maturity of adulthood, and yet here, Huck encounters a group of adults that are complicit in an endless cycle of death and violence. The acts of violence are not personally motivated but rather cyclical and obsessive, and neither side can ever truly win. In a profound moment of irony, Buck describes a time when both families arrived at church to listen to a sermon about brotherly love while holding their guns in their seats. Eventually, it is revealed that a Grangerford and a Shepherdson have fallen in love, emphasizing the absurdity of the feud. Evidently, the two sides are not drastically dissimilar, and it’s clear their rivalry is socially constructed and utterly pointless.