Marcus is a character introduced in The Scorch Trials film. He used to smuggle kids up into the mountains. Jorge thinks he is the one who knows the Right Arm's whereabouts, and beats him up to force him to tell him where they are.

The Scorch Trials film

In The Scorch Trials film, Thomas and Brenda are separated from the main group and decide to look for Marcus, who is someone who Jorge knows that knows about The Right Arm. Thomas and Brenda end up at a house where many people are congregating. They meet a man in a suit who tells them that Marcus used to own this house, but he died. He gets them both drunk and sends them into the party. After the party, Thomas and Brenda wake up to discover that Jorge and the group have found them. It is also shown that the man in the suit is actually Marcus. Jorge demands information from Marcus, and he says that he switched sides and works for WCKD, getting kids drunk and bringing the immune ones to WCKD. Jorge gets Marcus to tell him The Right Arm’s location, and Jorge takes his car, Bertha.

The Scorch Trials Official Graphic Novel Prelude

Marcus is seen in the graphic novel prelude to the film. Jorge brings Brenda to a Right Arm outpost and runs into Marcus first who drives them to the outpost. At the outpost, they meet up with Mary Cooper. WCKD attacks the outpost to ”collect specimens” that Mary was gathering and bleeding for WCKD’s work on the Flare. Marcus saves Jorge and Brenda, and offers to take Jorge to safety but not Brenda as WCKD is after kids. Jorge turns this down and Marcus leaves. Jorge and Brenda later escape through a sewer pipe. As the graphic novel is a ‘prequel‘ to The Scorch Trials film, this encounter with Marcus explains Jorge’s hostility towards him in the film.