Monastic Life and Office
According to the synaxarion, Theodosius became a monk at Constantinople at eighteen years of age before travelling to the Philotheou monastery on Mount Athos, where he pursued a strict ascetic discipline. Philotheou, founded by the Blessed Philotheus at the end of the tenth century, ranks twelfth in the hierarchy of the Athonite monasteries.
In 1375 he was selected to serve as igumen (abbot) of Philotheou. He was subsequently appointed Metropolitan of Trebizond, an elevation the tradition attributes to the holiness of his life. Philotheou numbers Theodosius among the notable figures associated with the monastery.
The Foundation of Dionysiou
As Metropolitan of Trebizond, Theodosius is remembered for encouraging the imperial house of Trebizond to support the establishment of the Dionysiou monastery on Mount Athos. The synaxarion names the benefactor as John Alexius Komnenos.
The Dionysiou monastery was founded in the mid-fourteenth century by Saint Dionysius of Korisos, whose brother served as Metropolitan of Trebizond; this family connection helped secure the patronage of the Trapezuntine ruler Alexios III Komnenos, the monastery's principal benefactor during its founding period. A chrysobull of September 1374, preserved in the monastery's archives, records Alexios III's stated wish to add a new Athonite foundation so as to live on in the memory of the people. The wider sources note that the Metropolitan of Trebizond in this period played a key role in connecting the imperial court of Trebizond with the monastic life of Mount Athos.
Some sources identify Dionysius's brother, the Metropolitan of Trebizond, without naming him; the correspondence of region (Koritsa near Korisos) and office makes the identification with Theodosius plausible, though it is not confirmed by every source.
