At the time, Mesarites was skeuophylax of the Church of the Pharos in the Great Palace of Constantinople, and wrote an eyewitness account of the events.
[2] As Metropolitan of Ephesus, he headed a mission in 1214/5 to Constantinople for discussions with the new papal envoy, Cardinal Pelagius of Albano.
Mesarites wrote a report of his discussions with Pelagius, where he highlights his intransigence, intolerance towards the Greek Orthodox clergy and insistence on Papal primacy.
[2][4] In 1216 he officiated at the marriage of Irene Laskarina, the eldest daughter of the Nicaean emperor Theodore I Laskaris, and Andronikos Palaiologos.
[5] Mesarites' writing style, distinguished by "his interest in vivid details and in his own role in the events" (A. Kazhdan), marks a conscious departure from the conventions of Byzantine literature, which he on occasion mocks.