The older brother is noted for his self-righteous and unforgiving attitude toward his younger brother. He reminds his father that he never strayed as did the younger son, had remained faithful throughout his life; yet the younger brother's return is accompanied by great rejoicing. He finds this both unfair and unjust. His attitude is exemplified in his haughty reference to "this son of yours" rather than to the younger as his brother.
The older brother represents the Jews who followed the Law and expected to be rewarded for their faithfulness; they criticized Jesus for eating with "publicans and sinners." The essence of the parable is one of grace: unmerited favor. The younger son certainly received more than he deserved; yet the point of the story is that all people who return to God the Father receive more than they deserve. The older brother's resentment is typical of those whose "holier than thou" attitude causes them to feel that those less diligent should receive less than they.