All that is known of him is found in the "Breviarium Aberdonense" and in the "Book of Deer", a ninth-century manuscript, now in the Cambridge University Library, but these two accounts do not agree in every particular.
Showing signs of a religious vocation he was entrusted at an early age to the care of St. Columba, who trained him and gave him the monastic habit.
According to the Celtic legend, Columba, his disciple Drostan, and others, went from Iona into Buchan and established an important missionary centre at Deer on the banks of the Ugie on lands given him by the mormaer or chief of the district whose son he had by his prayers freed of a dangerous illness.
Here his sanctity attracted the poor and needy, and many miracles are ascribed to him, including the restoration of sight to a priest named Symon.
[6] When St. Drostan died at Glen Esk his remains were conveyed back to Aberdour where they were deposited in a 'tumba lapidea' or stone coffin.