In "My Sister Stole My BF. She Didn’t Expect My Grand Revenge," the narrator deals with the betrayal of having their boyfriend taken by their sister. Initially heartbroken, the narrator plots a clever and surprising revenge that catches everyone off guard. The story explores themes of betrayal, sibling rivalry, and empowerment, ultimately highlighting the consequences of the sister's actions. The narrator's wit and determination lead to a satisfying twist, emphasizing the importance of standing up for oneself within complex family dynamics.