Above all, Dragon Ball and its successors are stories about fighting. While Goku has come to epitomize the ideal of the shonen hero, it is his relationships with others -- both violent and peaceable -- that have these ideals, both visible and cognizable. These themes particularly develop in Goku's relationship with his arch-rival and reluctant friend Vegeta. In the decades since his introduction, Vegeta has become one of the franchise's most beloved characters, in no small part due to how he has matured along with his audience. Beyond being a simple foil to Goku, Vegeta is without question the series' principal "deuteragonist" -- and arguably the greatest of any anime.
The essence of this deuteragonism is their opposed yet complementary approaches to the ideal of the fighter. Contrary to Goku, Vegeta's insecurity, pride and neuroticism make him a much more relatable and ultimately "human" character. Against Goku's untroubled and unconscious persona, Vegeta's internal struggles with his own doubt, frequent humiliations and changing life circumstances not only make him a fan favorite but provide critical contrast. In Dragon Ball Super, as Goku and Vegeta reach the end of a complex, shared character arc, the meaning of their contrast becomes clear.
"The State of the Gods": Goku in Dragon Ball Super
This long arc begins with Goku's inspiration, the character Sun Wukong from the 16th-century Chinese novel Journey to the West. In the novel, Sun Wukong is described as being "awakened unto emptiness." This is meant to be understood both lightly -- with regard to his clumsiness and intermittent buffoonery -- but also more abstractly with regards to the ego. From its inception, Dragon Ball parodically yet faithfully combines these ideas in Goku, culminating with "Ultra Instinct". In this technique, clearing his mind of fear, doubt and pride allows Goku's body to fight on its own.
In emulating this classical, supernatural persona, Goku becomes a less realistic and relatable protagonist. Yet the inherent difficulty of contending with this idealized lead is what makes Vegeta's rivalry with Goku a more spectacular, humorous and ultimately compelling form of deuteragonism. By specifically rejecting Goku's ideal, Vegeta is able to complement it and permit the story to mature beyond it.
"The Secret of the Self-Indulgent": Vegeta in Dragon Ball Super
In Dragon Ball Z, the Saiyans and Vegeta represent the contrast to Goku's lovable, simple-minded intensity. Driven by conflict, the Saiyans draw their strength from their legacy, sense of racial suprematism and their lust for battle. By the series' conclusion, however, the Saiyans represent something more: the destructive intensity of the Ego. In this sense, Vegeta represents the fullest extent of the Saiyan's power as well as the limit of an individual's willpower and desire.
Formerly sheltered in comfortable delusion as the Prince of All Saiyans -- and awoken by his nemesis-turned-friend Goku -- Vegeta's character arc is a long story of struggle to rebuild his fighting spirit from the manifest failure of his own "natural" superiority to his ultimate self-reconciliation through sheer force of will.
Past the many milestones, failures and tribulations, "Ultra Ego" represents the willful culmination of this process: Vegeta accepts and draws upon the intensity of his own anger, pain and his Saiyan lust for battle, putting everything he is into the fight. Such a powerful contrast to Goku and the classical ideal tells an ultimately richer story.
Goku and Vegeta, Yin and Yang
While Ultra Instinct and Ultra Ego correspond to Goku's and Vegeta's respective histories and personalities, their present role in Dragon Ball Super -- working to amend their violent legacy -- extends an arc that stretches past Dragon Ball and through to Journey to the West.
Like Goku and Vegeta themselves, these complementary ideals of fighting have inspired and enabled one another. So much so that the possibility of their harmonious integration -- again like the characters' begrudging and unbeatable friendship -- lends some hope to the positive resolution of their incredible shared saga.
