Mongooses appear throughout The Brief Wondrous Life of Oscar Wao as guardians of the family. Historically, the mongoose was imported from Asia during the 18th century. Mongooses were imported to tropical islands such as the Dominican Republic, Jamaica, and Hawaii. Used to protect sugar cane fields from rat infestations, mongooses were pivotal in the DR's growing sugar economy. While the mongoose is transplanted from Asia, it retroactively becomes a "norm" within the DR's plantation system. While the mongoose guides Beli, its presence is necessary for sugar production. The mongoose is known for its sociability and cunning. Like the de Leon family, the mongoose is an immigrant, an invasive, non-native species. The mongoose was transplanted westward to the Dominican Republic, just as Oscar’s family was forced out of the Dominican Republic. Diaz has stated the importance of the mongoose as being alien, creating an other-worldly quality to its assistance. Furthermore, in a footnote, the mongoose is described as “an enemy of kingly charriots, chains, and hierarchies... an ally of Man”, suggesting the mongoose’s importance in helping the de Leon family not just for their misfortune but also as a means of undermining Trujillo’s oppression.
At the most superficial level, the mongoose can be equated with the zafa, the counter-spell to the family’s fukú. For example, when Beli is beaten in the canefield, a “creature that would have been an amiable mongoose if not for its golden lion eyes and the absolute black of its pelt”  motivates Beli and sings to her to guide her out of the canefield. The creature acts as her protector, saving her after the atrocities just committed against her. The mongoose further stops a bus directly in front of her, preventing her from being hit and providing her transportation to safety. Similarly, Oscar remembers a “Golden Mongoose” which appeared just before he throws himself from the bridge  and again when he is beaten in the canefield for the first time. In the canefield, the Mongoose talks to Oscar and saves him just as Beli was saved. Furthermore, just as the singing mongoose leads Beli to safety, a singing voice leads Clives to Oscar.
This symbolic relationship is heightened by the transient nature of the Mongoose, disappearing as suddenly as it appears. Each time the mysterious animal appears in a time of dire need, the narrator includes a disclaimer on the accuracy in the visions of the creature. In the case of Beli in the cane fields, the narrator shares that whether her encounter with the mongoose “was a figment of Beli’s wracked imagination or something else altogether” cannot be determined (149). Whether or not this creature is a figment of the young woman’s imagination, it led her to safety and provided hope in a situation where death seemed imminent. In having this character take on such a surreal nature with characteristics not found in most mongooses, such as the ability to talk and vanishing in the blink of an eye, Diaz establishes an uncertainty that mirrors the controversies over whether superstitions exist. While the encounters with the creature may or may not have happened, their significance in the book still holds strong just like the superstitions, because “no matter what you believe, the fukú believes in you” (5). The connection between a superstition and a magical character is more easily followed than one with an ordinary animal, highlighting the mongoose being a zafa against the de Leon’s fukú.
Power of appearance
Beli understood how advantageous appearance is in the social situations of the Dominican Republic, but not until she had undergone major physical and psychological changes. Beli desired the same romantic experience as Oscar, despising school in her early years from being “completely alone” (83). Her loneliness derived from her “defensive and aggressive and mad overactive” personality that pushed people miles away from her. Unlike Oscar, however, her predicament reversed, becoming not one of a lack of power, but an abundance. She had to choose whether or not to take advantage of her new curvaceous body which puberty had generously bestowed upon her. With these new curves she was thrown into a world where she could get what she wanted, where she was given attention without having to ask for it. Her model-like body presented her with the relationships that she could have never attained otherwise. After recovering from her initial shock of the metamorphosis, she discovered how “her desirability was in its own way, Power” (94). She had been presented with a magical sceptre that allowed her to satisfy her desires. Asking her not to abuse that power was akin to, as Díaz says it “asking the persecuted fat kid not to use his recently discovered mutant abilities” (94). By utilizing her appearance, she gained a complete understanding of the influences of her body.
The power of appearance in the era of Trujillo can not be underestimated, as seen by its dangerous consequences in the de León family history. Abelard Luis Cabral, Oscar’s grandfather, learned this first hand after repeatedly refusing to bring his first-born daughter Jacquelyn to Trujillo’s events. Trujillo’s rapacity towards women knew no bounds, employing “hundreds of spies whose entire job was to scour the provinces for his next piece of ass” (217). Trujillo’s appetite for ass was “insatiable” (217), pushing him to do unspeakable things. His culture of placing appearance above all else does nothing to deemphasize appearance in Dominican culture, seeing as in a normal political atmosphere people follow their leaders, much less in the tightly controlled Trujillan dictatorship. Abelard, by withholding his daughter’s “off-the-hook looks” (216) from Trujillo, he was in effect committing “treason” (217). His actions eventually resulted in Trujillo arranging for his arrest and eighteen-year sentence, where he was brutally beaten and treated to an endless series of electric shock treatments (237). During his imprisonment, Socorro committed suicide, Jackie “was found drowned” in a pool, Astrid is struck by a stray bullet, and his third child is born (248-250). Abelard and Socorro’s third child, a daughter they name Belicia, was born “black”, a terrible thing for the Dominicans, who viewed having a child of “black complexion as an ill omen” (248). They felt so strongly about this that Yunior, offering his own opinion, comments “I doubt anybody inside the family wanted her to live, either” (252). She eventually was tossed around the extended family and eventually “sold”, yes “That’s right-she was sold” (253). All of these tragedies as a result of the desire for a beautiful young lady, a by product of the preeminence given to physical appearance.
Even under Trujillo, however, the power of appearance is called into the question, as appearance's power ultimately takes second place to the power of words. Cabral is incarcerated, tortured and almost destroyed at least in part as a result of words he has spoken and written, and Trujillo has Cabral's entire library, including any sample of his handwriting, destroyed. As Trujillo never attempts to sleep with Jackie, the narrator and reader are left to wonder if at some level the motivation for this family ruin has to do with silencing a powerful voice.
Reexamining masculinity through Yunior and Oscar
Yunior and Oscar are character foils that illustrate two different types of masculinity: if Oscar’s nerdiness, fatness and awkwardness make him the antithesis of Dominican hypermasculinity, then Yunior, as a Don Juan and a state school player who can “bench 340 pounds” (170), is the embodiment of that identity. They also have completely opposite values: while Yunior cheats habitually and can’t appreciate even the most beautiful and loving women, Oscar is faithful and sees beauty in a middle-aged prostitute; while Yunior doesn’t value sex for anything other than physical pleasure (at least not at first), Oscar refuses to go to brothels (279). Yunior’s masculinity echoes that of Trujillo, who in his violent actions and lust for women, also embodies Dominican hypermasculinity.
Despite their differences, Yunior and Oscar become important to each other and develop an unusual friendship. As Oscar has no father or brothers, Yunior is the only male with whom he can discuss his romantic yearnings; Yunior is his access into masculinity. As for Yunior, Oscar models an alternative form of masculinity and ultimately pushes him to reexamine his ideas about manhood. VanBeest points out that in spite Oscar’s lack of machismo, he possesses “other masculine traits that Yunior admires.”  For example, Yunior envies the way Oscar can develop friendships with women (like Jenni) and talk to them about non-sexual topics. He also respects Oscar’s writing style and his ability to “write dialogue, crack snappy exposition, keep the narrative moving” (173). Finally, although Oscar dies in the end, Yunior admires how he was able to achieve real intimacy with a girl by being loving, faithful and vulnerable. VanBeest argues that Oscar “succeeds in educating Yunior, indirectly, in the responsibilities of manhood; after Oscar’s death, Yunior claims that it is Oscar’s influence that encourages him to stop following the dictates of el machismo and finally settle down and get married.”  At the end of the novel, Yunior manages to develop a healthier form of masculinity that allows him to love others and to achieve intimacy.
Through Yunior and Oscar’s friendship, Díaz critically examines Dominican machismo and shows how it can lead to violence and an inability to connect with others. Through the figure of Oscar, he explores alternatives to hypermasculinity. If “fukú” is “[the] manifestation of the masculine ideals imposed on the Dominican Republic herself,”  then is Oscar the zafa of this fukú.
Filling the blank pages – stories as "zafa" for the fukú of violence
Throughout the novel, violence is transmitted from the system of colonialism and dictators to the domestic sphere and perpetuated through the generations. Virtually all the relationships in the book – Trujillo and Abelard, Beli and the Gangster, Beli and Lola, Oscar and Ybón – are marked with physical or emotional abuse. Violence is an aspect of the “fukú” or curse that haunts the Cabrals and de Leons.
Although at the end of the novel, none of the characters seem to have escaped the cycle of violence or the effects of fukú, Yunior has a dream in which Oscar waves a blank book at him, and he realizes that this can be a “zafa” (325) to the family curse. Yunior also has hope that Isis, Lola’s daughter, will one day come to him asking for stories about her family history, and “if she’s smart and as brave as I’m expecting she’ll be, she’ll take all we’ve done and all we’ve learned and add her own insights and she’ll put an end to it [the fukú]” (331). Yunior implies that storytelling is a way to acknowledge the past and its influence over one’s life, a way to make sense of what has happened, and is the starting point for healing.
In an interview with Edwidge Danticat, Junot Díaz comments:
"For me, though, the real issue in the book is not whether or not one can vanquish the fukú—but whether or not one can even see it. Acknowledge its existence at a collective level. To be a true witness to who we are as a people and to what has happened to us. That is the essential challenge for the Caribbean nations—who, as you pointed out, have been annihilated by history and yet who’ve managed to put themselves together in an amazing way. That’s why I thought the book was somewhat hopeful at the end."