 He was said to be cynical about politics and believed that politics was a "ballgame of the rich".He started participating in politics when his brother Ninoy, was assassinated in August 21, 1983 at the Manila International Airport in Pasay.Under the administration of President Ferdinand Marcos, Agapito was one of the founders of the August Twenty One Movement (ATOM) and Bansang Nagkakaisa sa Diwa at Layunin (BANDILA).