The central twist of "El Infierno" is the revelation of who was responsible for the death of Benny's brother, "El Diablo." Throughout the film, it is assumed that he was killed by the rival cartel, Los Panchos. However, Benny eventually learns the devastating truth: his brother was tortured and killed by their own boss, Don José Reyes, for sleeping with Don José's wife. This revelation dismantles the illusion of loyalty and honor within the cartel, exposing it as a world of pure self-interest and brutality.
An even more tragic turn is the discovery that Benny's young nephew, "El Diablito," has been acting as an informant for the rival cartel. He did this to avenge his father's death after discovering that the Reyes family was the true killer. This twist underscores the theme of cyclical violence, as the boy has already been consumed by the same world that took his father. It also adds a layer of tragic irony to Benny's attempts to protect him.
The film's ending is deliberately bleak and cyclical. After surviving being left for dead and discovering Lupe's murder, Benny takes his revenge by massacring Don José and his corrupt associates during the Bicentennial celebration. However, in the film's final moments, an unnamed young man, the grandson of the rival cartel's leader, shoots and kills Benny. The very last shot shows "El Diablito" visiting the graves of his family before driving off, implying he is now fully committed to the narco life to continue the cycle of vengeance. This ending solidifies the film's core message: there is no escape from this hell, and the violence will endlessly perpetuate itself.