Today is the feast of Pope St. John I, who had an interesting career, although we have only sketchy knowledge of it. Flourishing in the early sixth century, he seems to have been a deacon for quite a long period of time; a deacon for the diocese of Rome was in some ways a major ecclesiastical position at the time. Early in his career there was a big schism in Rome in the aftermath of the Council of Chalcedon. The Byzantine Emperor was trying to push a compromise, and the Byzantine governor, who was still a major figure in the selection of the Pope, had promised a candidate who would be willing to compromise. Unfortunately for the governor, his preferred candidate died while the governor was in Constantinople, and the governor wasn't able to find a candidate who could get the same approval of the Roman clergy. The clergy split between supporting the Archdeacon Symmachus and the Archpriest Laurentius, who were each elected by different factions on the same day. The schism led to actual violence between the two groups; the king, Theoderic, summoned them to Ravenna to decide the matter and decided in favor of Symmachus, on the grounds that he had been elected first and had the most supporters, despite the fact that Laurentius was probably the candidate he would have himself preferred. (The Laurentians claimed that Symmachus bribed Theoderic's officials.) The schism, of course, did not magically disappear. We know that John was an active supporter of the antipope Laurentius, but he reconciled with Symmachus in 506 or so.
He seems to have become a good friend of Boethius. Boethius dedicated several of his theological works to a 'Deacon John', who is almost certainly the same John; and some of Boethius's remarks in passing suggest that they discussed difficult theological matters together. Unbeknownst to them both, history was stepping toward their doom with the ascension of Justin I to the imperial throne in 518. Both Orthodox and ruthless, Justin quickly brought to an end the imperial policy of pushing compromise over the Council of Chalcedon and forced a resolution to the Acacian Schism. He then began cracking down on heresies, first the Monophysites, and then, in 523, the Arians. The thing of it is, Theoderic, like most of the Ostrogoths, was Arian. Boethius was appointed to Magister Officiorum (the most important civil official in the Western Roman Empire) in 522 and Pope John I was elected to the papacy in 523. In response to Justin's decrees against the Arians, Theoderic sent a delegation to Constantinople to negotiate toleration for the Arians. John at the time was elderly and sick, but Theoderic forced him to head the delegation, apparently threatening to engage in reprisals against Orthodox Christians if John failed to get adequate toleration for the Arians -- and Theoderic seems to have had quite a long list of demands.
Despite his frailty, John apparently was quite successful at negotiating a toleration for the Arians; we don't know exactly how the Pope chose to go about his negotiations, and Justin wasn't willing to compromise on everything, but the emperor did accept much of the Pope's advice. In the meantime, Theoderic imprisoned and executed Boethius on suspicions of treason, almost certainly because he was a major figure among the Catholic Orthodox in the West. And when John returned from Constantinople, Theoderic seems not to have been satisfied; Theoderic imprisoned the Pope in Ravenna, where he slowly died from ill-treatment in prison. John died on May 18, 526, and was commemorated as a martyr.