A good protagonist should have a ghost that haunts him or her. Or, to use a less dramatic expression, a trauma. Something that happened in the character's past and is still influencing his behavior and his way to see the world. It often is a traumatic experience like the early loss of a beloved one, or an accident in his or her childhood, but it can also be something positive. It depends on the story we wish to tell, and what story we wish to tell depends on us. I found out pretty late that I tend to tell stories whose protagonists have paternal ghosts. The "ghost" of my "Rebecca" protagonist, "I", was her father, just like the ghost of "Elisabeth" and "Mozart!". And my latest heroine, "Lady Bess", has to leave two ghosts behind, those of her father, Henry VIII, and her mother, Anne Boleyn.