Erwin was a complex character, portrayed as serious, calculating, and always planning far in the future. While he trusted his men, he was the first to realize that there was a spy interfering with the Survey Corps, and was able to come up with a reasonable criteria to determine which of his soldiers to trust with vital information, and which to keep in the dark. An eloquent speaker, Erwin was able to sway many people, such as the military tribunal held to judge Eren and the trainees.