Another sign of those with an "elder brother" spirit is joyless, fear-based compliance. The older son boasts of his obedience to his father, but lets his underlying motivation and attitude slip out when he says, "All these years I've been slaving for you." To be sure, being faithful to any commitment involves a certain level of dutifulness. Often we don't feel like doing what we ought to do, but we do it anyway, for the sake of integrity. But the elder brother shows that his obedience to his father is nothing but duty all the way down. There is no joy or love, no reward in just seeing his father pleased.
In the same way, elder brothers are fastidious in their compliance to ethical norms, and in fulfillment of all traditional family, community, and civic responsibilities. But it is a slavish, joyless drudgery. The word "slave" has strong overtones of being forced or pushed rather than drawn or attracted. A slave works out of fear -- fear of consequences imposed by force. This get to the root of what drives an elder brother. Ultimately, elder brothers live good lives out of fear, not out of joy and love.
Tim Keller, The Prodigal God [pp. 57-58]