Exploring the Complexity of Peter in History and Legend

Jesus' closest disciple was Simon, whom henicknamed "Peter" -- that is "The Rock." But in the Gospels and the writings of Paul, Peter is fickle, clumsy, and unreliable, less like a rock than shifting sand.

After the New Testament we have numerous writings both about and allegedly by him. In looking over all these records, what can we say about the one on whom Jesus allegedly "built his church"? Is it possible to separate out the history from the legend? The fact from the fiction? And why didn't the Gospel writers do a bit more to improve his reputation?