" The recovery of the sheep is through penance"
The word is repent (to change one's mind for better, heartily to amend with abhorrence of one's past sins) Luke 15:7, "I say unto you, that likewise joy shall be in heaven over one sinner that repenteth, more than over ninety and nine just persons, which need no repentance." It does not carry the idea of penance but a change of the will.
The prodigal son is just an elaboration of that. It was not the sons feeling sorry or doing anything to earn the father's disposition towards him, just his coming home, "he was lost, now he's found".Luke 15:22-24, "But the father said to his servants, Bring forth the best robe, and put it on him; and put a ring on his hand, and shoes on his feet:
And bring hither the fatted calf, and kill it; and let us eat, and be merry: For this my son was dead, and is alive again; he was lost, and is found. And they began to be merry."
Notice the Greek conjunction "but" that limits what the son is doing and changes the emphasis of the parable to what the father is doing. He could care less what the son is saying or doing, just that "my son was dead, and is alive again; he was lost, and is found". For that, there is joy in the house.
Sorry for the dealy in responding; I will catch up as much as I can today.
That is a tangent to the issue that the sheep are supposed to repent (whatever precisely, that repentance entails). It is therefore somethigng that happens to sheep: they are lost. Therefore, the security that you impute to the same sheep in John 10 is imputed without warrant: sheep do get lost, sometimes they are found, and sometimes they are lost forever.
The Protestants like to make much of the literal meaning of "metanoia", "changing the mind", and the Catholic concept as penance. So, in what sense does the Gospel use the word: does it mean a purely intellectual changeover, or does it involves some penitential work? If we look at how St. John the Forerunner used the word, we have to go with the Catohlics: he wore a hairshirt, lived as a hemit, and fasted. That was the example of "metanoia" he gave. You do your own math.
It was not the sons feeling sorry or doing anything to earn the father's disposition towards him
The repentance of the son is what brought him home. His arrival produced forgiveness. It is notable that it is his suffering in the body (eating with the pigs, etc.) that produced the change of heart.