Adventius (bishop of Metz)

[4] Pope Nicholas I (858–867) however, called for another council in 863 at Metz, which his legates would attend alongside Lotharingian bishops, along with specific criteria listed in his Commontorium that needed to be met in order for his approval that the decision for Lothar to divorce Theutberga was legitimate.

However, the wrath of Nicholas was invoked when he learned that his legates had been bribed, and when two of Lothar's leading supporters Archbishops Gunther of Cologne and Theutgard of Trier travelled to Rome in October to present the findings of the Council, Nicholas excommunicated the pair, annulled the decision of the Council, and demanded all other Lotharingian bishops who had supported Lothar to explain themselves or risk being excommunicated themselves.

Lothar refused to accept this decision from the pope until 865, when he reluctantly remarried Theutberga in the presence of several leading counts and bishops, with Adventius included in this ensemble.

Charles the Bald quickly had himself crowned at Metz by Adventius on September 9 869,[10] claiming a large amount of Lothar's previous territories in the west of Lotharingia.

[11] Writing a generation later, Regino of Prum says Charles was easily able to inherit a large portion of Lothar's kingdom due to the ‘ingratiated’ influence of Adventius.