Some notes on the parable of the prodigal son, or "sons", as Tim Keller referred to this passage in some of his messages. Most of these are notes taken some some of his Redeemer sermons (many of which are free from here.)
In Luke 15 Jesus tells the parable of the prodigal son, but the story is actually built around two sons. The younger one wants to leave and requests an early inheritance, basically the same as wishing his father dead. the analogy being built here is of one being ungrateful to God's goodness.
The younger son leaves, spends all of the money, and ends up feeding pigs, and even envying their food (and eating with pigs would have been highly taboo and shocking to the Jewish audiences.) Realizing his fallen state, the younger son decides to go home and, as he's returning he prepares what he will say in terms of an apology. Yet on the way home the father rushes to him, interrupting the son's apology message (here speaking about the fact that there is no stipulation on his return.
The younger son is welcomed back, but the story doesn't end here. The older brother refuses to celebrate with the father and younger son. Again here is an example of a son shaming his father, by refusing to be part of the banquet. The father appeals to the older son to come in, and the curious thing about the parable is that we don't know what happens. Does the older brother come in? We never find out, as the parable ends, a new chapter begins and Jesus starts telling a different parable.
One message about the younger son is that it can speak to the mentality of those who merely stay at church until they get what they want, and then they leave. This parable isn't just about "bad" people out there, but can speak to virtually anyone in the church who sees it with a mentality of "what will I get out of this?"
The older brother speaks of legalism and being faithful to the law, yet at the same time being lost by blind, rigid obedience to works-based righteousness. In this story, both brothers were lost and, at the close of the story, we only know that one of the brothers was saved.