Jesús Arrabal is a Mexican anarchist that Oedipa and Pierce met on their trip to Mazatlán. He was affiliated with a group known as Conjuración de los Insurgentes Anarquistas (CIA—hardy har har, Pynchon). While wandering through San Francisco in the middle of the night, Oedipa meets him again by chance in a Mexican restaurant. Arrabal informs her that he is now in exile.
Oedipa remembers that Arrabal hated Pierce, who "played the rich, obnoxious gringo so perfectly that Oedipa had seen gooseflesh come up along the anarchist's forearms" (5.87). Yet, after Pierce left the two of them on the beach, Arrabal told Oedipa that Pierce was "an anarchist miracle" because he was "too exactly and without flaw the thing we fight" (5.88). Oedipa now wonders if Arrabal would have stayed with the anarchists "without the miracle of Pierce to reassure him" (5.89).
Arrabal's first name makes the obvious reference to Jesus Christ (although Jesús is a common name in Latin America). "Arrabal" might reference a couple of things. First, it is Spanish for "suburbs" or "slums," which could make his whole name "Jesus of the Slums." Second, it might refer to the Spanish playwright Fernando Arrabal Terán, whose work has been described as brutal, cacophonous, and wildly political—much like Pynchon's own. Like many names in Pynchon's work, it is so loaded with reference that a scholar could write a ten-page paper unpacking it… or it could just be a practical joke.
Arrabal appears very briefly in the novel, but he seems to serve a specific purpose. In order for him to sustain his extreme philosophy, he must clearly be able to imagine the Big Bad or Other—that which he fights against. A theme that runs through the novel is that American radicals have a great deal of trouble imagining what exactly the thing they oppose is. The result is that there are a bunch of radical movements without unity or coherence. Arrabal provides something like a brief vignette illustrating the need to clearly imagine the Big Bad/Other.