What was Mazers and Enders relationship like in enders game?

Mazer is Enders teacher during enders game. he trained him to beat the formics. [SPOILER] he made ender think that he was testing him with games when ender was actually fighting in the war. They first met on Eros, the asteriod where Command School was held. In the book Ender In Exile they are companions who are close during the begining of the book before Ender leaves for Colony 1 (later named Shakespeare