With no power to annul the elemental evil in him, though readily enough he could hide it; apprehending the good, but powerless to be it; a nature like Claggart’s, surcharged with energy as such natures almost invariably are, what recourse is left to it but to recoil upon itself and, like the scorpion for which the Creator alone is responsible, act out to the end the part allotted it.See Important Quotations Explained
If Billy represents innocence in the novel, the older, higher-ranked Claggart represents evil. Claggart’s innate wickedness is causeless and seemingly limitless. His motives are far more sophisticated and subtle than Billy can comprehend. Billy lacks awareness of the discrepancies that exist between human action and human intention, always taking actions at face value; Claggart, on the other hand, exhibits a great understanding of deception and ambiguity and makes frequent use of them in his nefarious plots—for instance, he shows kindness toward Billy to mask his unkind intentions.
Because Claggart carefully hides his own motives and intentions, he has a tendency to assume that other people are also motivated by hidden malice, and he overinterprets the actions of others in order to find the ill will concealed within them. Deeply egocentric, Claggart obtains sustenance from envy. When Billy spills the soup, Claggart assumes that Billy has purposely directed this action toward him, utterly ignoring the obvious indication that Billy simply spilled by accident. Seeking to destroy Billy, Claggart employs underhanded and vicious methods, falsely accusing Billy of mutiny in order to see him killed.
In the novel’s Christian allegory, Claggart represents Satan, working tirelessly to pervert goodness and defeat morality and human trust. On another level, Claggart represents the serpent that tempted Adam and Eve in the Garden of Eden. When Claggart’s false allegation prompts Billy to strike him violently, Claggart has effectively coaxed Billy into abandoning his virtue and committing an evil deed. Indeed, the narrator refers to Claggart’s corpse as a dead snake. Thus, it is possible to interpret Billy’s death as a double victory for Claggart: Billy dies, as Claggart wished, and he falls from moral grace, as well.