On first reading, Louis might seem like one of the play's villains, abandoning his lover at the time of his greatest need. But although Louis has human failings and commits an immoral act in leaving Prior, he is no villain, as Act II, Scene One helps us to understand. The depiction of Prior's illness is truly awful. The screams in the night are frightening, and Louis's panic is entirely justified: Prior refuses to go to the hospital, but there is no way Louis can help him. He cannot even perform the simple task of cleaning his body, since Prior's blood is infectious. In addition to this physical and medical helplessness, the scene conveys the emotional difficulties Louis must suffer. The gentle, witty Prior of years past is replaced by a person who screams and cries, shouts at Louis for touching him and faints without warning—he is entirely self-centered, which is understandable but difficult for his lover. Faced with such a constant nightmare, Louis's actions become more comprehensible. Kushner has said that at a time when an inadequate health care system and longer life expectancy are forcing more and more Americans to care for aging or sick relatives, he wanted to dramatize the simple truth that not everyone is a born healer and caretaker. Louis's eventual abandonment of Prior is extreme and selfish but, as this scene shows, perfectly human.
Louis's problem is exacerbated by his tendency towards abstraction and his unreasonably high standards for himself. In Scene Three, he tells Emily about La Reine Mathilde, who supposedly created the Bayeux Tapestry. Louis describes La Reine's unceasing devotion to William the Conqueror and laments his own comparative lack of devotion. But as critic Allen J. Frantzen has pointed out, this popular story about Mathilde and the tapestry is wrong—it was actually created in England decades after the conquest. Louis, then, is holding himself to a mythological standard of loyalty, and he curses himself based on a positively unreal example. This is part of a larger pattern of excessive guilt and harshness toward himself, which, paradoxically, prevents him from judging his own weaknesses accurately and trying to correct them. Because no one could possibly live up to Mathilde's example, Louis initially justifies his moral failure. Later, in Perestroika, he will arrive at a more genuine remorse and an honest understanding of what he has done.
Louis's conversation with Emily has another important function: it establishes Prior's ancient and very prestigious lineage. Whereas Louis's ancestors were rootless immigrants, Prior's family is the epitome of stability, so much so that the sons all even bear the same name. What's more, as Mayflower descendants they must be socially prominent and possibly wealthy—especially since, as the notes on the characters reveal, Prior lives off an inherited trust fund. But this unbroken line will come to an end in our Prior: as a gay man, he will have no children, and as a person with AIDS he likely has only a short future left. Since he rarely works, he will not even add to the family's store of capital. The image of the tapestry provides a metaphor for the family line—Prior represents the breaking of the thread. No wonder he might be attracted to the idea of halting the cruel march of history, since more than the other characters, with their obscure or impoverished immigrant backgrounds, Prior has something to lose.