Christian Böck is first introduced as a somewhat suspicious-looking character, a member of a borderline-illegal car club who is not even trusted by his club mates. During the course of his investigation into this club, Moser begins to suspect Böck, but he turns out to be an undercover policeman making similar investigations. The two eventually combine to solve the relevant case, and Moser convinces Böck to transfer to his team. Böck's undercover skills are largely ignored after the transfer, but his personable manner proves an advantage when it comes to interrogations (particularly contrasting with the somewhat dour Moser). By the time of Brandtner's arrival, Böck's youth and athleticism have resulted in his frequently being involved in chasing criminals on foot. The dynamic between Böck and Kunz forms an almost constant source of comic relief. Most notable in this is their dialogue when trying to establish the angle from which a witness would have seen a certain event - each man speaks at cross-purposes to the other and both end up totally confused. Böck and Rex share a rivalry, with Böck trying to outsmart Rex, but Rex wins nearly all the time. Böck is also one of the few who question Rex's abilities as an elite police dog, but Moser keeps telling him that he has always been this way.