Marcus has a round face, dark skin, short brown hair that is receding and a goatee.
He wears a blue baseball cap and a lighter blue short-sleeved shirt alongside a pair of beige shorts with brown sandals that have a single strap across the foot.
He seems to be easy going and calm under pressure, as shown during his and Zack's fishing trip with Martin and Milo. Initially, he was skeptical of the existence of Murphy's Law, attributing the mishaps to things like 'inexperienced casting'. But once things really started going wrong he was quick to help.
He loves to scare his son and has been doing so all of Zack's life.
Before Zack and Milo met
He was shown in a flashback with his son and his wife on a boating trip where Zack got scared by a fish that landed on their boat ("Murphy's Lard").
Marcus, Zack, Milo, and Milo's dad went on a fishing trip on Murphy's Yaw. At first, he doesn't believe in Murphy's Law, but throughout the day he eventually believes in the Murphy family curse ("Time Out").