Early Life and Monastic Career
Serapion originated from Pekhorka, a village in the Moscow region now identified with Pekhra-Pokrovskoye, part of Balashikha in present-day Moscow Oblast. He married and was ordained a priest, but was widowed within a year of his marriage.
Following his wife's death, he was tonsured a monk at the Dubensky Dormition Monastery in Vladimir province, where he eventually became hegumen. He subsequently served as hegumen of the Stromynsky Dormition Monastery; both institutions were later liquidated in the eighteenth century. In the mid-1490s he assumed leadership of the Trinity Monastery, later renowned as the Holy Trinity-St. Sergius Lavra.