Grounded and Uncle Remus

Jack Potter is back with Harry for their second year at Hogwarts. Jack was grounded all summer at Remus' place when it wasn't a full moon. So Jack could not send letters only receive them. When Jack heard Harry wasn't answering his letter, Jack got worried. But is relieved to see Harry is ok in Diagon Alley. This year there will be attacks on muggle borns. Everyone will think Harry is the heir of Slytherin. How does Jack help protect Harry this year?