Yun-Zhen is an airbender during the time the temples still flourish and are full of life. He, too, is full of that same life and is very humorous. He likes to think himself the wittiest of the group, but often he is just the most ridiculous. He tends to act very light and buoyant, however, his thoughts always dwell in dark places. He gets drawn into these darker states occasionally through his thoughts, but he never lets anyone take him there. Yaru prefers to have fun with his friends than for them to know of his true nature. He becomes a good ally to Avatar Thaddeus over time, and even tries to teach him  airbending. He has a relatively high voice, and occasionally has voice cracks too. He sounds young and excited when he is happy, however, when he is drawn into the dark he talks slower and emptier.