Mercutio du Marchege is a character in the anime adaptation Romeo x Juliet. He is a young nobleman and a friend to Romeo Montague, though his loyalty is complex and driven by personal ambition. Mercutio is depicted as ambitious, sly, and snarky, with a sharp tongue and a contemptuous attitude toward common people. His primary motivation is a deep desire for power and status, which stems from his resentment toward his father, Titus, a Montague advisor whom Mercutio views as weak and inadequate. This resentment makes him susceptible to the manipulations of the powerful Lord Montague.

In the story, Mercutio is initially tasked by Montague to spy on Romeo, keeping tabs on his activities. He also shows a degree of interest in the character Hermione, though whether his feelings are genuine or whether he intends to use her as a pawn in his schemes remains ambiguous. After Romeo is banished, Mercutio agrees to be adopted as Montague's new heir, believing this will secure his future. However, the initiation into this role is traumatic: Montague kills Titus in front of Mercutio, and Mercutio, paralyzed by fear, does nothing to save his father. This event haunts him, filling him with guilt and trauma, and he swears loyalty to the bloodied Montague out of fear rather than conviction.

As Montague's reign begins to crumble, Mercutio attempts to seize an opportunity to redeem himself and gain praise. He stabs Montague and attempts to rescue Juliet, expecting to be hailed as a hero. Instead, he is coldly dismissed by Tybalt, who leaves the scene in mad laughter, leaving Mercutio stricken and his expectations shattered.

Mercutio's role in the series is that of an antagonist and a tragic figure whose ambition leads him into a web of manipulation, violence, and psychological damage. Key relationships include his fraught dynamic with his father Titus, his uneasy servitude to Montague, his friendship-turned-surveillance of Romeo, and his ambiguous connection to Hermione. His development traces a path from a calculating, power-hungry young man to a traumatized and guilt-ridden individual who ultimately fails to secure the recognition he craves. He possesses no supernatural abilities; his notable traits are his cunning intellect, his capacity for deception, and his skill in navigating the political intrigues of his world.