@Agabus
I think one of the strongest arguments for Papal Supremacy is that at least a few of the Fathers have unambiguously taught at least some elementary form of that doctrine. Yes, there are plenty of those bad Patristic quote-mining fueled by a host of non-sequiturs, combined with the Peter-syndrome. Yes, there are many quotes that are ambiguous and leave room for either a pro-Orthodox or a pro-Catholic interpretation. But a select few, in my opinion, leave little to room for any other rational interpretation other than Papal supremacy. Irenaeaus and Optatus comes to my mind. A few Father's opinions does not make doctrine, but I wonder why they have not been rebuked by other Christians back then, if what they said was unorthodox. Have they just ignored them? Possibly, but it's also just as possible that they silently agreed with them.
You'd really have to provide citations for your Iranaeus and Optatus allusion for this to become a useful argument.
Optatus, Against the Donatists:
1:10
"Now there is another question: For what purpose have you mentioned those who have not the Sacraments which you and we alike possess? Sound health does not clamour for medicine; strength which is secure in itself does not need outside help; truth has no lack of arguments; it is the mark of a sick man to seek remedies; it is the sign of a sluggard and a weakling to run in search of auxiliaries; it belongs to a liar to rake up arguments. To return to your book, you have said that the Endowments of the Church cannot be with heretics, and in this you have said rightly, for we know that the churches of each of the heretics have no lawful Sacraments, since they are adulteresses, without the rights of honest wedlock, and are rejected by Christ, who is the Bridegroom of One Church, as strangers. This He Himself makes clear in the Canticle of Canticles. When He praises One, He condemns the others because, besides the One which is the true Catholic Church, the others amongst the heretics are thought to be churches, but are not such. Thus He declares in the Canticle of Canticles (as we have already pointed out) that His Dove is One, and that she is also the chosen Spouse, and again a garden enclosed, and a fountain sealed up.
Therefore none of the heretics possess either the Keys, which Peter alone received, or the Ring, with which we read that the Fountain has been sealed; nor is any heretic one of those to whom that Garden belongs in which God plants His young trees. Concerning these men, that which you have written at length (although it has nothing to do with our present business) is abundantly sufficient."
2:2
"You cannot then deny that you do know that upon Peter first in the City of Rome was bestowed the Episcopal chair, on which sat Peter, the Head of all the Apostles (for which reason he was called Cephas), that, in this one chair, unity should be preserved by all, lest the other Apostles might claim----each for himself----separate chairs, so that he who should set up a second chair against the unique chair would already be a schismatic and a sinner."
2:4
"It is a branch of your error growing out of a lie, not from the root of truth. In a word, were Macrobius to be asked where he sits in the City, will he be able to say on Peter's chair? I doubt whether he has even set eyes upon it, and schismatic that he is, he has not drawn nigh to Peter's 'Shrine,' against the precept of the Apostle who writes.....
Behold, in Rome are the 'Shrines' of the two Apostles. Will you tell me whether he has been able to approach them, or has offered Sacrifice in those places, where----as is certain----are these 'Shrines' of the Saints."