His Eminence, Metropolitan Demetrius of America, was born Victor Kiriacou on November 15/28, 1974, in Toronto, Canada, to pious parents Constantine (who was tonsured a monk with the name Naoum prior to his repose) and Chrysoula Kiriacou from Vevi, Florina, Greece. He is the third of three children.

After spending time in the Holy Land and on Mount Athos, he entered the Monastery of the Holy Transfiguration in 1994 and was tonsured, receiving the name Demetrius (named after his ancestor, the priest Demetrius) in honor of St Demetrius of Thessaloniki. He was ordained to the diaconate in 1999, the priesthood in 2005, and the episcopacy in 2006. In September 2012, he was received into the canonical Church of the Genuine Orthodox Christians of Greece together with a number of clergy, monastics, and parishes throughout the United States, and elected Bishop of Boston, concelebrating with His Beatitude, Archbishop Kallinikos of Athens and all Greece, and those hierarchs with him on September 8/21, 2012. On September 20/October 3, 2012, the feast of St. Eustathios, he was elected Abbot of Holy Ascension Monastery in Bearsville, NY, in the presence of His Beatitude, Archbishop Kallinikos, and five other hierarchs of the Synod from Greece and America. On February 6/19, 2014, he was elected Metropolitan of America.

On Sunday, April 28/May 11, 2014, His Eminence was enthroned as Metropolitan of America at the Cathedral of Saint Markella in Astoria, New York by His Eminence, Metropolitan Gerontios of Piraeus and Salamis, representing Archbishop Kallinikos of Athens and All Greece and the Holy Synod.

On Tuesday, September 30/October 13th, 2015, the feast of the uncovering of the relics of St John of Shanghai and San Francisco, His Eminence founded the monastery in honor of the same saint, a staunch defender of traditional Orthodoxy. The name of the monastery was chosen by lots, during the Divine Liturgy. The monastery treasures relics, clothing, vestments, personal items, and correspondence of St John, as well as many other holy relics (around 200). It is the residence of His Eminence, who is also functioning as the abbot of the holy monastery.

His Eminence speaks English, Greek, various Slavic languages and some Spanish and French.