Marco is a Tower Kid and part of DogNut's crew that travel across London, he is originally from the Imperial War Museum along with DogNut, Felix and Jordan.
Before the Disease
Nothing is known about Marco's life before the disease broke out, though it is likely he was friends with Felix at the time.
During the Disease
Marco was at the Imperial War Museum in The Dead, though he isn't named and only recognised by his German WWII helmet. He later move to The Tower of London after the fire and Battle of Lambeth Bridge. He becomes a Pathfinder and works with DogNut, Felix and Courtney. Marco fights with a spear and has a knife as a secondary weapon.
Before the Books
It is mentioned in The Dead, when Ed is speaking to Jordan that he along with the others living there had to fight some adults to live in the Imperial War Museum, and that they lost a few people to take it. It is likely that Marco was one of the ones who helped Jordan take the Museum.
Life at the Imperial War Museum
Little is known about Marco's life at the Imperial War Museum, though it is likely he trained regularly with his weapon of choice. He is known to work as a guard for Jordan, as he is one of the ones standing guard when the Coach kids arrive.
Life at the Tower
Not much is known about Marco's life at the Tower, though it is likely he was a Pathfinder as he is one of DogNut's best friends and would have worked with him. It is likely he didn't have many, if any girlfriends at the Tower as he is friends with Felix, who most dislike, and also as that is his main reason for going with DogNut to the Tower.
Note; this is chronologically the last book Marco appears in.
Marco is one of the bodies discovered by Blue and the Holloway fighters after they save Brooke. He is mutilated and barely recognisable and so they hide his and the others bodies in some bushes before continuing. His name is never given in the book, but it is revealed to be him in The Fear.
Marco is never named in The Dead, but is known by his German World War II helmet. He lets the Coach kids into the Museum along with another boy who is supposedly Felix. He along with DogNut, Jordan and Felix, leave the Museum towards the end of the book due to the fire and sickos, and helps fight towards Ed and eventually, along with the others makes his way to the Tower of London.
Marco is one of the more major characters in The Fear, and it is the first time his name is fully mentioned. He is best friends with Felix, despite the fact they always argue, and is kind to people, whereas Felix is mean. He adventures with DogNut and the others across London, out of loyalty for his friend DogNut and also because he is interested in finding some girls. He carries a spear and a knife.
He helps row up the the river and goes with the others to the Houses of Parliament. As they make their way from the Houses of Parliament to Buckingham Palace they are attacked by a tough group of sickos known as Gym Bunnies, and Marco drops his spear, and so instead uses his knife. He has it taken from him by the leader of the Gym Bunnies and so grabs his spear again. They are saved by a tough crew of street kids called "Hunters' led by a boy named Ryan. Ryan helps the Tower kids out and takes them to the Palace for free.
At the Palace, David doesn't want them to leave so later that day he escapes the Palace along with DogNut, Felix, Courtney, Finn, and Olivia, and calls Felix a "wanker" when he says to leave Olivia as they escape from a mob of sickos. The group is trapped in a house by a fat, hording sicko known as the collector. He manages to survive the Collector's house and manages to make it to the Natural History Museum. Once there he offers to go with DogNut and a large group of fighters back to the Collector's house to kill the Collector.
When they reach the Collector's house he is asked to go with Felix and three others from the Museum and check the ground floor of the house. Whilst doing this he finds Olivia's head along with Felix, and scorns Felix for joking about the kids deaths, though he shows understanding as to why he did it. Along with Felix he eventually helps force the Collector from out of his house by burning things and making a lot of noise. He then takes part in killing the Collector.
Upon returning to the Museum he decides to leave along with DogNut, Felix and Courtney, but has to stay along with the others so that they can have their stories written down in the "Chronicles of Survival". The next day they finally leave and are escorted by Robbie and Jackson, and some others from the Museum. Along the way however they are ambushed by the Gym Bunnies and Marco eventually is knocked down next to Felix, who was blinded by the lead mother wielding Marco's knife, and the Gym Bunnies kill them. He grabs Felix's hand and tells him that he is there with him, as they both die.
Marco's appearance is largely undescribed, though he is likely good looking as he could be popular. He commonly wears a German World War II helmet and likely has other armour, though it is never mentioned. He is likely fifteen or sixteen.
Marco is stated to be kind and caring, being nice, a complete contrast to Felix, though despite this they remain best friends. He is kind to Olivia when she talks about her brother Paul, and tries to help her when she is almost left behind as they escape a mob of sickos on their way to the Natural History Museum. He seems to enjoy swearing and getting into arguments with Felix, and neither seem to be able to let the other have the last word.
German Helmet - Marco's most recognisable feature is his German World War II helmet, which he got from the Imperial War Museum.
Spear - Marco's main weapon of attack, he uses a spear for stabbing at enemies, and is likely skilled with it as he is one of the best fighters.
Knife - Marco uses a knife as a side weapon, and it is the first thing he draws upon losing his spear, though he quickly loses his knife too.
Felix - Marco's best friend, they never seem to be able to stop arguing and are constantly mocking each other, but despite this they are extremely close and caring for each other, such as when Marco waits for Felix as they escape the Collectors house and when he holds Felix's hand as they both die. He seems to be one of the only people who understands Felix, as most consider Felix cruel and horrid, Marco knows he only does it to cope with what they have to go through.
DogNut - Marco appears to be very loyal to DogNut, and follows him across London in search of their missing friends. DogNut refers to Marco as "the good" due to him being kind, and being Felix mean.
Courtney - Not much is known of Marco and Courtney's relationship, although they seem to get on a lot better than Courtney and Felix. She takes his side in his and Felix's argument, but she quickly becomes annoyed at him when he tells her to stay out of it. She seems to find his bickering with Felix very annoying.
Jordan Horden - Not much is known of his relationship with Jordan, though he likely has the same respect for him as DogNut does, and is likely loyal to him for the time he has spent following his orders.
Ed - Not much is known about his relationship with Ed, though he likely respects his fighting ability.
Finn - Marco and Finn seem to be on good terms, as they both can joke about and help each other.