As TAIRA no Kiyomori came into power after the Hogen Rebellion and the Heiji Rebellion, Suetada get acquainted with Kiyomori as his cousin-in-law (the mother of Suetada's legal wife (the daughter of MINAMOTO no Yoshitada) was an aunt of TAIRA no Kiyomori).
その後、保元の乱、平治の乱を経て、平清盛が権力を握ると、季忠はその義理の従兄弟（正室の源義忠の息女の母は平清盛の伯母にあたる）として接近した。