Yugo Amaryl was a mathematician from the Dahl sector of Trantor . He was Hari Seldon ’s closest friend and associate, and the two of them laid the foundations of Psychohistory together, especially in the early years of Psychohistory’s development. Amaryl was seen as Hari Seldon’s natural heir as the head of the Psychohistory project, but pre-deceased Hari by some years, dying at the age of 52.


Yugo Amaryl was born on raised on the Dahl sector of Trantor. He is first encountered in Prelude to Foundation , during Hari Seldon’s Flight. Initially, he is a heatsinker, working in the heatsinks beneath Dahl. These heatsinks were Dahl’s main source of prestige in the Empire, as they were great sources of energy. However, working in the heatsinks meant menial, physical labor in uncomfortable conditions. Thus, heatsinkers were ostracized on Dahl’s more well-off residents, who saw them as brutes.