Demelza Robins joined the Gryffindor Quidditch team as a chaser in Harry Potter and the Half-Blood Prince. According to Harry, she is excellent. She was exceptionally good at dodging Bludgers. She was the one who delivered a message from Severus Snape telling him about his detention which happened to be on the same time as Professor Slughorn's party, much to Harry's distress. Crowds wait outside a Borders store in Delaware for the midnight release of the book Harry Potter and the Half-Blood Prince is the sixth novel in J.K. Rowlings Harry Potter series. ... A bludger, a jet black ball that rockets around the quidditch pitch. ... Spoiler warning: Severus Snape (born January 9, circa 1960) is a fictional character in the Harry Potter series of novels. ... Horace Slughorn is the current Potions Professor in Harry Potter and the Half-Blood Prince. ...