Father and Two Sons (Luke 15)

"Father and Two Sons" in Luke 15 is one of the three ”lost” parables in Luke: the lost sheep, the lost coin, and the lost son. Is this an allegorical story or just a family story with two parts, the younger son and the older son? The main theme is the father’s compassion. We need to analyze characters: the father's behavior as not very adamant about his sons and his unconditional acceptance of his son; the older son/brother as a diligent son; a prosecutor-role; the younger one as immature and selfish; not truly repenting, but returning home to survive. Reconciliation will happen eventually? What are the conditions for it?