St Theophanes the Confessor was a Byzantine monk/abbot, historian who lived 758/760 – 12 March 817/81 and served the Imperial court. In his Chronicles he does not shy away from his high view of the papacy in passing.
When he learned this, the pope convened the full numbers of the church and went to the grave of the chief of the apostles--St Theophanes, Chronicle AM 6121 (section 332) found in the translation by Harry Turtledove, 1982. The Chronicle of Theophanes (A.D. 602-813), page 33
The Emperor was furious at the pope and at the defection of Italy. He armed a great expedition and, appointing as its commander Manes the general of the Kibyrhaiot theme, sent him against the pope and the Italians. But the irreverent fellow was put to shame when the expedition reached the Adriatic Sea. Thereupon Leo the enemy of God raged all the more, for he was under the control of his Arabic heart. He levied a third more tribute on the people of Sicily and Calabria. He also ordered the patrimony of the saints and princes of the apostles (who are honored in the elder Rome), which from ancient times had paid three and a half talents of gold to the churches, to pay them to the public account.--St Theophanes, Chronicle AM 6221 (section 408) found in the translation by Harry Turtledove, 1982. The Chronicle of Theophanes (A.D. 602-813), page 100
In the elder Rome Gregory, a holy and apostolic man who held the same throne as had the prince Peter, caused Rome, Italy, and all the west to secede from both political and ecclesiastical obedience to Leo and his Empire.--St Theophanes, Chronicle AM 6224 (section 410) found in the translation by Harry Turtledove, 1982. The Chronicle of Theophanes (A.D. 602-813), page 101
In this matter they opposed the holy scriptures in every respect. For if Peter the prince of the apostles killed Ananias and Sappheira solely for lying, and the great Paul said with a shout, “Those who do such things deserve death” (which he said about bodily sin alone), how would not those who release from the sword men who are absolutely impure in spirit and body and who worship demons be enemies of theirs? But the pious Emperor Michael cut down not a few of these heretics.--St Theophanes, Chronicle AM 6304 (section 495) found in the translation by Harry Turtledove, 1982. The Chronicle of Theophanes (A.D. 602-813), page 174-175
In one episode he records the heretical Emperor attempting to force Patriarch of Constantinople Makedonios to renounce the council of Chalcedon:
The emperor put pressure on Makedonios, bishop of Constantinople, to anathematize the Synod of Chalcedon as Helias of Jerusalem had done. But Makedonios said that without an ecumenical synod under the presidency of the bishop of Rome it was impossible to do this. As a result, the emperor, out of hostility to him, ordered that those who sought refuge in the Church be dragged away by force, while providing rights of asylum to the churches of heretics.--St Theophanes the Confessor. The Chronicle of Theophanes Confessor: Byzantine and the Near Eastern History, A.D. 284-813. 151, book pages 233. United Kingdom, Oxford University Press, 1997. Found in Migne PG 108:360a
Hardly Byzantine flattery.