On multiple occasions he has been known to take quick action in protecting his family from threats and known or unknown enemies.
He is well trained in many forms of martial arts which is seen throughout the series on multiple occasions both when he has fought Doyle,Van Rook and various other foes.
He can be seen as harsh, strict, overbearing, and aggressive towards Zak; however, this is most likely because he is worried about his son and the dangers in the line of work he is in. He is very much a loving man and shows his affection more with actions than words.
In "The Return of Tsul 'Kalu" it is revealed that Zak was unwittingly responsible for the damaging of Doc's right eye. When he was very young, Zak accidentally destroyed a sacred site. Tsul 'Kalu was the site's protector, and went after Zak. The Saturdays escaped on the Airship, but Tsul 'Kalu got on and went after Zak, Doc found him and convinced Tsul 'Kalu that Zak was too young to know what he had done and that being his father Zak's mistake was his responsibility. Doc and Tsul 'Kalu battled on top of the Saturdays HQ during a thunderstorm, 'Kalu used a Claw pendant from one of his prey to electrocute Doc which damaged his eye, gave him his scar, and shocked a large part of his hair white. Doc still managed to defeat Tsul 'Kalu, and in return Tsul 'Kalu gave Doc his claw pendant, which Doc later gave to Zak. To keep Zak from feeling guilty, Doc and Drew told Zak that Doc lost the use of his eye in an accident.
- According to Doc in "Curse of the Stolen Tiger," he met Drew while rock climbing.
- It is known that Zak is the cause of the scar over his eye and the white in his hair.