Again according to Campbell (I won't quote but just paraphrase) - the male hero - our boy, Charlie, usually receives any number of charms or magic this and that from female helpers. These gifts, although they may be helpful and pleasing at the time of giving, are really important latter on in the adventure. The hero must use these "helper charms" at crucial times when he is trying to gain the ultimate prize in the adventure.
Charlie receives gifts from two female helpers, his mother, Margaret and his sweetheart, Rocky. In Chapter Fourteen, The Compass and the Key, Charlie is handed his grandfather's compass and the key to his grandfather's diary. As helpful and necessary as both are in Book One, they will, of course, turn out to be more than just an old, family compass and the key to his grandfather's diary. They will turn out to be "magical helpers."
Another gift that Charlie receives is the locket that is given to him by Rocky. This occurs in Chapter Seventeen, Saying Goodbye. Rocky gives Charlie a locket that first belonged to her parents. Their initials had been inscribed on the case. When Rocky hands the locket to Charlie, the two lover's initials had been inscribed as well. (These two sets of inscriptions are important) - Charlie doesn't understand the entire journey, of course, and he certainly does not understand the significance of the locket but he will. The four initials are a clue, quite naturally, to help him solve certain elements in the adventure. So, the compass, the key to his grandfather's diary and the locket are helping "amulets" that Charlie will need latter on. In mythology, this is a way for the male hero to "derive hope and assurance from the helpful female figure..." ("Hero with a Thousand Faces" - page 130)
The reader will have to wait for Book Two to find out what happens here. You'll like it :)