Marco is a young child from Skies of Arcadia. He is poor and alone. He first loathes the Blue Rogues, but later grows to accept them as friends.
When Marco is first met in the game, it is in Lower Valua, and he is quite hateful of Vyse, Aika and Drachma and doesn't understand why'd they'd come to a place like Lower Valua. Vyse calls him obnoxious, so Marco swears that he'll make them pay. He attempts to turn them in to the Valuan guards, but Vyse stops him. Marco is pessimistic because he lives in the sewers of Lower Valua and feels there is no reason to continue living anyway. He gains hope when he witnesses the defeat of the Valuan Executioner. Although he warns Vyse that the blue rogue will probably get caught eventually and tells him the story about how his parents had tried to escape Lower Valua and were arrested and executed, Vyse tells him that giving up without trying is not his policy.
He is met again much later in the game when the crew gains the Delphinus, Marco hides on board so he can go with them. Vyse quickly discovers him, but lets him come along anyway.
Marco is not a playable character, but he may or may not serve a role in air ship combat as well as in the Blue Rogues Special S-move. Marco is the first crew member you get, and his position in the crew is "sailor".
In air ship combat, if he is in your active crew, then you can use him in Crew Command to restore twice as much SP. It costs eight SP to use.
In the Blue Rogues Special S-move, Marco picks a huge booger and flings it at enemies.
In the Crescent Isle Base, Marco will be in the room underneath Vyse's and Enrique's bedrooms with Hans and Pinta. If Vyse talks to him, then Marco will tell him that he never expected the sky to be blue. In Lower Valua, it was always stormy with black clouds, so he never knew that sky was actually so pretty. Then he'll yell at Vyse to stop laughing at him. Also, Merida mentions that she finds it hard to hate all Valuans because she met Enrique, who's so nice, and because she met Marco, who is so cute.