Rachel and I listened to Tim Keller's sermon on Luke 15- Keller points out that 'the prodigal' son is a misnomer because the parable is about two sons and the father's love and forgiveness of them both; the first for disobedience and the second perhaps for pride.
I have often related better to the elder son - the one who served faithfully and felt unrewarded. Many of us have 'followed the rules' and served without feeling like we have received the reward or affirmation we have earned. From the 'reward' perspective the father in the parable (and by interpretation God) seems unjust and unconcerned about obedience. I have a hard time reconciling 'what you sow you will reap' or the parable of the talents to this rewarded delinquent scenario; it seems like the younger son had his cake and ate it too! My sympathy has always been with the older brother, and from man's perspective the story isn't fair! Why doesn't the older brother receive his reward?
Keller explains that both sons were guilty of a lack of love for the father. The first through rebellion, the second through a false righteousness that sought reward not relationship. They both missed out on relationship with their father and it was that relationship which was the true reward.
Perhaps the church in Corinth was not unlike these two brothers. The church struggled with corruption and immorality not unlike the younger brother but it also contained the older brother, arguing over whose gifts were greater and worth more recognition. The Apostle John makes a case for the first son lacking love (John 5:3-4) and Paul clearly addresses the lack of love of the second in 1 Cor. 13. Both the elder and the youger as well as the church in Corinth were missing out on the blessing of obedience because obedience without love is profitless and love without obedience is false.
I also consider the older brother's motivation. One could easily imagine him to be disdainful or bitter because his compassion is not for his brother who has humiliated his family through his folly. Instead of running to embrace his brother and inquire about his well being and welcome him home; the elder immediately takes offense at the father's display of affection. Regardless of any hypothetical history between the siblings, the clear answer is that the motive of the elder was not love. Nor was his confrontation of his father in such a public and ridiculous way. Perhaps the younger did not return from a motive of love, but he did present himself with humility. The self-justification of the elder might have been justified in the harm done him, but he forfeit the reward he claimed through the very way he claimed it.
Which brings us back to the application - the ultimate reward is our relationship with the Father who has given us all good things. It seems obvious that rebellion would hinder that relationship, but less obvious to the 20th century reader is the understanding that the older brother through rightness had distanced himself as far from the father as the younger. One might speculate that because the actions of the elder were done without love he missed out on the joy of the giving, and because love was not his motive, he could not accept the goodness with which his prodigal brother was received. Myself, similarly must wrestle with the motivation of my obedience and the recognition that my bitterness toward others I deem to be less deserving of good fortune only indicates my lack of love. I am not suggesting that we will accept every slight with no pang of frustration, nor that we place ourselves in situations where our temptations toward selfishness might draw us away from love, but that we consider how similar we all are in our sinfulness and that we refocus on our relationship with the Father as our greatest reward and that we judge our opinions of deserved reward by the measure of love, not gifting or self-sacrifice, etc.