Piandao had risen through the ranks as a remarkable killing machine who, at the ripe old age of twenty-seven, had single-handedly dropped more bodies than anyone had since the war began. Some of those bodies had been Fire Nation. To be fair, they started it!
Piandao was a specially-trained super soldier possessing unique skills and an uncanny ability to size up and adapt to any situation. But his most redeeming quality was that he never spoke unless he had something useful to say.
He was also a dishonorable prick.
At Piandao's last posting, he decided that his captain was an idiot who would get them all killed so Piandao usurped his command by turning the other men against him, issuing orders that countermanded Captain Shu's. He then demoted his former captain, ordering him to return to boot camp for more training. His unmitigated gall notwithstanding, Piandao got results and Shu was, in fact, a flaming idiot. So it was decided by Prince Iroh during Piandao's last disciplinary hearing that the young upstart should be given a "wide berth".
"Success", the Dragon of the West declared, "is to be rewarded, not condemned."