Yen'fay has an old fashioned and serious personality and enjoys meditation. He has deep loyalty to his country as he was willing to join forces with the Valm empire to stop further bloodshed of innocent lives. However, much of his loyalty was actually due to his love and care for his younger sister, Say'ri. Because of a deal struck with Excellus, Yen'fay begrudgingly obeyed the man who murdered his parents just to keep her safe. Yen'fay refused to tell Say'ri of his plan to ensure her safety.
