Paul's letter to Philemon provides guiding principles for a master responding to a run-away slave who has wronged the master in some way.  The principles apply to all relationships.  1) There is no room for an attitude of superiority.  We are all equal at the cross. 2) We need to practice radical forgiveness because we have been radically forgiven. 3) Brotherly love as described in I Cor 13 is to characterize our relationships.  The specific outworking of these principles is left open by Paul allowing room for the relationship to be shaped by the uniqueness of the individuals.