Who is David Ferrie from Libra and what is their importance?

David Ferrie is a pilot who once taught young men to fly and possibly sexually abused a few of them. Ferrie is an odd character, a lonely man who has a rare disorder that causes his hair to fall out. Ferrie tells everyone he has brain cancer. Ferrie knew Oswald as a child and is therefore chosen to be the one to contact him and guide him when the plot to assassinate the president begins to unfold. In the end, Ferrie convinces Oswald that it is his destiny as a Libra to kill President Kennedy.