A primer of the material? Uh, the story of David, as told in the the books of Samuel of the Old Testament (or Hebrew Bible, but one can assume the show is coming more from a Christian perspective). Which I think is one of the greatest and most affecting stories of power and kingship and corruption and love and loyalty and betrayal ever told. But then, I grew up enmeshed in Scripture, for all that I'm an atheist now.

Uh, primer: http://en.wikipedia.org/wiki/David#Biblical_narrative (of which only "David is chosen" and "David and Goliath" are relevant to the pilot episode)

But you probably also want to look at: http://en.wikipedia.org/wiki/David_and_Jonathan (Because David and Jonathan are second only to Achilles and Patroclus for great foundational gay icons of western literature)

Or, you know, just ask me in chat.