Although not much is known for Saints Erastus, Olympas, Herodion, Sosipater, Quartus and Tertius , we do know they are of the 70 first Apsotles of Christ.
The Apostle Paul wrote about Olympas and we also know that the Apostle Peter was near to him as well. St Rhodian has a similar relationship, as he was very close with Apostle Paul and he went with Peter to Rome, leaving behind his position as Bishop of Patras.
On the same day and during the same hour of Saint Peter’s crucifixion, both Saint Rhodian and Olympas were beheaded, giving their souls unot the Lord.
Of the other three we commemorate on this day, Saint Sosipater was the Bishop of Iconium. He served for many years before dying with peace. Saint Tertius was then the second Bishop of Iconium and we learn this from an Epistle where Paul spoke to the Romans. He died there as well with peace.
Saint Quartus did suffered many trials for the faith and through his loyalty to Christ and brave spirit eh was able to convert many of the idolaters to Christianity. Although he suffered tortures, he died in peace after serving as Bishop of Beirut.