The Fall of the House of Usher: How did Madeline kill Roderick?

In the final episode of The Fall of the House of Usher, titled "The Raven," it is revealed how Madeline Usher kills her brother Roderick. Madeline and Roderick, after making a sinister deal with Verna, are left with the task of fulfilling their end of the bargain. Madeline, desperate to escape her fate and continue living, tries to find a loophole in the deal. However, Roderick takes matters into his own hands to ensure that Madeline fulfills her part of the pact.Roderick poisons Madeline, mimicking the embalming process of an ancient Egyptian queen. Madeline seemingly dies and is placed in a sarcophagus. However, Madeline's rage and desire for revenge against those who have exploited her resurfaces, and she emerges from her supposed tomb. In a parallel to the show's opening episode, Madeline chokes Roderick to death in front of Auguste, their grandfather and the father of Roderick's deceased wife.This culmination of events brings down the Usher dynasty, with both Madeline and Roderick meeting their demise. With the Usher family extinguished, the epilogue of the series reveals the aftermath of their downfall. Juno, someone unrelated to the Ushers by blood, inherits Fortunato Pharmaceutical and uses the wealth to start a foundation aiding those struggling with addiction. Arthur Pym, who refused a deal with Verna, becomes the sole person arrested in the government's case against Fortunato Pharmaceutical.Auguste Dupin, the investigator who unearthed the Ushers' secrets, retires and enjoys a peaceful life with his family. He visits Roderick's grave, leaving behind a tape recording of their conversation as a futile gesture in the face of their collective demise. Verna, taking the form of a raven, returns items belonging to her victims as reminders of their lives and deaths.Thus, the story of the Usher family comes to a close, marked by their descent and the destructive consequences of their actions. The fall of the House of Usher serves as a cautionary tale about the dangers of greed, manipulation, and the pursuit of power. It also highlights the enduring themes of Poe's work, showcasing a modern interpretation of his gothic horror and psychological exploration.