Courtesy name Yide. Zhang Fei is an oath brother to Liu Bei and Guan Yu, him being the youngest of the three. He is among the most powerful warriors of his era, and is more sneaky than people would assume. When not overshadowed by the Eight Geniuses, he takes on the role of a capable military advisor.
Zhang Fei is more Machiavellian than his second oath brother Guan Yu. He's not afraid to play the fool, make deals under the table, injure or manipulate his oath brothers if it means accomplishing the goal, which is to help Liu Bei rise to power.