The Patronus Charm comes from the Harry Potter series, where Harry learns Expecto Patronum in The Prisoner of Azkaban to defend himself against Dementors, creatures that drain happiness. His stag Patronus becomes one of the most recognisable symbols of the franchise, repeated across later books and films whenever hope defeats fear. Clips of the incantation spread through fan edits, reaction videos and soundboards, where the familiar words work even without visuals. It endures because it is instantly recognisable, emotionally uplifting and tied to a beloved coming-of-age moment.