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.  The Yen'fay from the alternate timeline suffers from survivor guilt. He constantly degrades himself for allowing his dear sister to die and stood by and defended her grave as a form of atonement before being thrown into the present timeline. Although he is happy to see that his sister is alive in the current timeline, he cannot bring himself to associate himself with her due to his sorrow. Nevertheless, this Yen'fay still cares deeply for his sister, however much of his motivation is to atone for his weakness and make sure that Say'ri lives a happier life this time.