In this podcast, we see Goliath, David's giant enemy, is, like so many others in 1 Samuel, a serpent. This podcast also begins to discuss how these different "serpent" stories relate to each other. We find that these three serpent stories are not just random stories scattered throughout 1-2 Samuel. Instead, they appear at key points in the story of 1-2 Samuel to heighten our hope that one day Jesus, the son of David, will defeat the serpent and save his people forever.
Here's a link to Brian's book The Serpent in Samuel: A Messianic Motif. Sign up for Hands to the Plow's newsletter.