Could the father in "the parable of the lost son" really be profligate, even in offering love? "Abandoned to vice or vicious indulgence; recklessly licentious or debauched," the Shorter Oxford says; "broken down in morals or decency" (from Latin "to dash to the ground"): Webster's Second. And Dr. Johnson, cited in SOED:
Profligate in their lives, and licentious in their compositions.
Whereas being prodigal is a minor sin in comparison, "wastefully lavish","lavish in the bestowal of things" SOED. Webster's gives it as
One who spends or gives prodigally; a spendthrift; a squanderer; often
a repentant waster like the prodigal son; as, to receive the prodigal
with joy. Noble prodigals of life. Archbishop Trench.
In the very effective retelling in the Prokofiev/Kochno/Balanchine ballet, the son, after being fleeced by revelers and a siren, crawls back on his hands and knees to the father, who is remote and unbending and only at the last minute will he give his blessing. In the original parable the father sees the son coming from a distance and runs to meet him, to the extreme disapproval of the older brother.
Incidentally the Greek word πορνῶν that the brother utters, usually translated as prostitute or harlot, is catamite in the first entries of Liddell & Scott, becoming genderless in NT usage - bringing to mind perhaps Nietzsche's quip about God's Greek language skills.