It is said that after the deaths of his brother Tokihira and MINAMOTO no Hikaru (a court noble), who together had undermined Michizane, when Emperor Daigo became prone to illness and his father, the Cloistered Emperor Uda, returned to government, Tadahira achieved rapid advancement as his advisor.
逆に兄・時平や共に道真を陥れた源光(公卿)が亡くなり、醍醐天皇が病気がちとなり、天皇の父である宇多法皇が再び国政に関与するようになると、忠平は法皇の相談役として急速な出世を遂げたと言う。