Marco Gonzalez is a diehard fan of The Ooze, a comic book villain with the power to sludge his enemies. During his first visit to Horrorland, he came accross Chiller House and found a solitary copy of "The Wizard of Ooze" and brought it home with him. But after he paid a visit to a comic convention, things have been starting to get pretty weird for him. The Ooze (thought to be a man in a costume) was following Marco wherever he went, and The Fabulous Flame (Sammy) started showing up in random places, and even took the book.
Marco teamed up with The Ooze to take the book back (he'd practiced a few superpowers from it), but his powers were weak against The Fabulous Flame, due to his brother, Zeke, taking the bookmark (which gave stronger powers). Zeke defeated the two supervillains and Marco kept the book safe behind a loose panel in his wardrobe. Marco was then taken to Horrorland again after he touched the glowing Horror Jonathan Chiller gave him when he got the book.
Marco and some other kids who got souvenirs from the Chiller House were transported to Chiller. He asked them to play a game where they have to find the little Horrors (that transported them to his shop) so they can go home. He says Hunters are going to start hunting them the next day. He gives them Helper Cards so they can find their Helpers to help them find the horrors. They soon find out they can't leave the park without throwing away their Helper Cards. They soon get back their Helper Cards at a cart selling sushi-flavored ice cream.
They escape and split in groups: Ray and Sam, Andy and Meg, Marco and Jessica. Sam and Ray soon find Ray's helper who leads them to a joke red box. After meeting Chef Belcher, they find Marco and Jessica and they find out that the arrows are real. Then they run into Andy and Meg. When they find Madame Doom, Andy goes in her place and gets hit by an arrow, but reveals he's still alive and that the arrow was fake and Madame Doom wanted to make the game more "frightening". Andy says he didn't want to scare his friends, but Doom made him do it.
Madame Doom reveals that the Helpers were actually the Hunters. They flee and soon find out that Chiller is playing all the Hunters. He tells them the game isn't over yet, but they are sick of all this. Chiller also tells them that he never had any friends as a kid, so he made his own, and this entire plan was to prove he is a great hunter just like his dad wanted. The children then put on Chiller's costumes and say they're leaving him. Chiller yells at them to stop messing with his friends. He tells the kids that they can leave using the toy horrors. They do so, as Ray says bye to the others.
Marco is a twelve year-old male who acts mature and serious (everyone tells him that) and has a penchant for superheroes and comic books. He takes any and every scenario and talks about it in the context of a comic book.
Marco is tall and dark and serious looking, with a slender, serious face, black hair and dark eyes.