Peer had wavy hair and the thin outline of a mustache. During missions, he wore the standard Scout Regiment uniform.
Peer appeared to be a very serious and dutiful individual. He seemed to be a trusted member of the Scout Regiment, being given commanding positions during operations when Erwin could not be present. He could also often be seen personally escorting and assisting Erwin Smith on scouting missions.
He placed a great emphasis on authority, growing angry if other soldiers questioned or objected to orders they were given. He also seemed to be very loyal, placing himself in great danger in order to keep Erwin safe after the latter was injured while in Titan territory.
Peer participates in the 49th Exterior Scouting Mission, accompanying Commander Erwin Smith during the expedition and acting as his assistant. Peer is present when Section Commander Hange Zoë pleads with Erwin for permission to capture a Titan for testing.
During the 57th Exterior Scouting Mission, Peer reports on the number of soldiers whose bodies were unable to be retrieved to Erwin. Erwin orders Peer to list them as missing in action, prompting an objection from Dieter and Jurgen, who want to recover their friend Ivan's body. Dieter accuses Erwin and Levi of lacking any human feelings and Peer grows angry at the insult, demanding that the two soldiers show respect to their superiors.
Shortly afterward, Peer rides on the back of the wagon carrying the soldiers' corpses en route to Calaneth District. He spots two Titans pursuing the wagon, and fires a smoke round to signal alert the Regiment to their approach. Under Levi's instruction, the corpses are dumped to reduce the weight of the wagon and subdue the approaching Titans.
Peer is among the Scout Regiment soldiers who participate in the mission to rescue Eren Jaeger from Bertholdt Hoover and Reiner Braun. When Titans are spotted during the mission, Peer reports the sighting to Erwin. He reports more sightings, but Erwin is unconcerned. Upon reaching the Forest of Giant Trees, Erwin orders his soldiers to break off from each other and prioritize rescuing Eren over engaging Titans.
After the Scouts recover Eren, they begin to retreat to Wall Rose but are soon stopped when Reiner begins using his Titan form to throw Titans into their escape path, blocking them. Erwin is knocked off his horse in the ensuing chaos, and Peer is devoured while trying to protect him.
During the Battle of Shiganshina, as Erwin Smith begins to lament the dwindling hopes of his dream, Peer stands among the many fallen Scout Regiment comrades in Erwin's mind, wanting to know if their deaths had meaning.