QUOTE : By the time of the Final Battle, Harry discovers two more ways to handle dementors, and we see evidence that Snape probably used these tactics to seal his own mind against them. The Resurrection Stone gives Harry one way. The almost solid forms of Lily, James, Sirius, and Lupin keep him company on his walk toward death. These are the parents and family friends whose care instilled love in him so that he could have the kind of joy in life that can produce a Patronus. Not everyone is fortunate enough to have such riches. Not everyone is unfortunate enough to lose many of their loved ones so early. These intense memories of beloved caretakers are the sort of emotion that Patronuses are made of. Just thinking about them is protection enough.