In Quentin Tarantino's "Pulp Fiction", the character Vincent Vega, portrayed by John Travolta, is shown using heroin on several occasions. His drug use serves multiple purposes in the narrative and characterization. Firstly, it provides an immediate insight into Vincent's character, painting him as a man who's unfazed by the law, potentially reckless, and struggling with addiction, yet able to maintain a misunderstood sense of control. Vincent's nonchalant usage and casual conversation about heroin standards in different countries shows it as a part of his everyday life, painting him as a hardened criminal. Secondly, his drug use adds a level of unpredictability and vulnerability to his character, further developed in scenes like the adrenaline shot sequence with Mia Wallace. His drug-induced haze also plays a role in other key plot events, such as his misjudgment leading to Marvin's accidental death and his untimely demise in Butch’s apartment. Moreover, Vincent's drug use is contrasted with Jules' spiritually-driven choice to quit 'the life', drawing a stark difference between their characters' paths. Lastly, in a thematic context, Vincent’s heroin use represents the prevalent vice in the gritty underbelly of Los Angeles that Tarantino aims to portray in the movie. The drug use is not necessarily a tool of character development but more a character and narrative device used to highlight certain elements of his personality, impact the story, and anchor the film in its grim and morally complex universe.