A fan told JK Rowling on Twitter that she has been dealing with really bad things and was trying to stop self-harming. She said that Joanne helped her in her darkest times and asked Jo to write "Expecto Patronum" so she can have it tattooed on her scarred wrist.
Person’s Meaning Behind The Tattoo: The Spell Actually Means I Await For A Protector” In Latin. In The Harry Potter Itself, â€˜expecto Patronum” Is Used To Repel Dementors. Dementor Is The Guard Of The Azkaban Prison, A Dark Creature That Absorbs Your Joy