In Sherlock season 4, episode 3: "The Final Problem" why does Eurus want to torture Sherlock? What is her motive?
It is revealed that as children, Sherlock had redbeard as a friend. She wanted to be a part of it but that does not happen. She kills redbeard. But she does not do anything to Sherlock. That suggested to me that was the end of her revenge. Why does she want to torture Sherlock after 20+ years then?