Adrian was a member of a noble Roman family, related to Popes Stephen IV and Sergius II.
[6] Adrian sought to maintain good relations with Louis, since the latter's campaigns in southern Italy had the potential to free the papacy from the threat posed by the Muslims.
At this council, Adrian was represented by legates who presided at the condemnation of Photius as a heretic, but did not succeed in coming to an understanding with Ignatius on the subject of jurisdiction over the Bulgarian Church.
[6] Adrian supported the work of Cyril and Methodius in Moravia, and authorized the use of the new Slavic liturgy.
[6] Arsenius' son Eleutherius married Adrian's daughter, having withheld the fact that he was already espoused to another.