Don Juan Triumphant is the name of a fictional opera written by the title character in the novel The Phantom of the Opera. In the 1986 musical The Phantom of the Opera by Andrew Lloyd Webber, the concept is expanded as an opera within a musical and the performance of it plays a major role in the storyline. The fictional piece draws major inspiration from the Mozart's famous work Don Giovanni yet the Phantom's opera is depicted as far more bleak and dark.
In the novel The Phantom of the Opera by novelist Gaston Leroux, Don Juan Triumphant (French: Don Juan triomphant) is an initially unfinished piece that Erik, the Phantom, has been working on for a period of over twenty years. At one point, he remarks that once he completes it, he will take the score into the coffin he uses for a bed and simply never wake up. Erik plays a section of his opera following his unmasking at the hands of Christine Daaé, who is stunned by the power of the music. As she describes it, the music takes the listener through every detail of suffering of "the ugly man," taking her into the abyss of the wretched torment and misery Erik has experienced in his life. The piece, in Daaé's view, makes pain divine. At the end, it takes a rapid ascent out of misery whirling up into a triumphant and victorious flight as 'ugliness', lifted on the wings of love, dared to look 'beauty' in the face.
Erik's choice of title and use of "Don Juan" is never truly explained, so it remains subject to various interpretations. Initially, when Christine sees the score and asks him to play it for her, Erik gets highly defensive and tells her never to ask him that again. The Phantom remarks that she is lucky not to come to that kind of music yet, as his Don Juan "burns" with fire not from heaven and would consume anyone who came near it. Whereas Mozart's and Lorenzo da Ponte's original Don Giovanni, inspired by vice and love affairs fueled by pettiness, will only make one "weep". After the Phantom is unmasked and his hideousness is revealed, Erik spitefully, and probably sarcastically, remarks that he is the same kind of man as Don Juan, because once a woman sees him, she loves him forever. He yells to her that he is "Don Juan triumphant". Eventually he crawls into his room to play his masterpiece to "forget the horror of the moment." Christine is so moved by what she hears that for a fleeting moment she believes that his hideous appearance no longer matters, although her opinion soon changes.