The father in the story of the prodigal son required no proof of repentance. God's love is stronger than his vengeance, as seen in Hosea 11:9.It also teaches us that the Father's love does not depend on our actions, and He loves us unconditionally.
To Davobrian, perhaps we could think of some of the offenses we have particular difficulty forgiving. Do we give others a second chance? Take, for instance, the ex-convicts, do we give them a chance to reintegrate themselves back to society without discrimination?
The younger son travels a journey similar to all Christians. We sin and fall from grace but the Holy Spirit within us constantly reminds us to return to the father, and when we are spiritually dry, we will return. Yet, when that happens we also yearn for our brothers and sisters to welcome us, not only the Father.