"Sector Q kick his aft!" - Mario giving a seemingly simple command to his team.
Mario appears in Sixth Age, being Sector Q's de facto leader.
In the story Crutch, Mario and the remaining members of Sector Q tried to stop Teen Tornado from terrorizing a group of kids at a nearby park. After their initial assault failed, with Numbuh 112 getting thrown into a tree and Numbuh 414 getting stuck in a trash can. Mario and Numbuh 414 then got thrown around like rag dolls while Numbuh 112, with the assistance of Nolan York, defeated Teen Tornado. After cleaning up the park Mario and Nolan became friends.
A week later, after Numbuh 112 turned thirteen and was decommissioned, Mario, Numbuh 414, and Nolan were attacked at the Sector Q tree house by a group of teen ninjas led by Prom Queen and Teen Tornado. After the destruction of their tree house and Nolan's capture, Mario and Numbuh 414 resolved to hit the teens hard and rescue Nolan. Armed with the only working 2x4 tech they had, they assaulted the teens at James Woods Regional High School. After a long fire fight the duo of operatives eventually gained entrance to the high school. To cover more ground, the duo split up.
Mario searched the Gym and ran into Teen Tornado. Mario and Teen Tornado fought it out in the Gym and eventually gained the upper hand. But just as Numbuh 414 arrived with Nolan, the ceiling of the gymnasium collapsed on Mario and Teen Tornado.
A few hours later, Mario was rushed to the closest KND medical facility by Nolan and Numbuh 414. Later after his operation, Numbuh 5CC concluded that Mario wouldn't be fully healed till he was fourteen. With weary faces Numbuh 414 and Nolan watched as their friend was carted away by decommissioning operatives.
Mario reappears in the story "Agenda" set two years after "Crutch" and goes by the call-sign 'Joker'. He is shown to be in a wheelchair due to the injuries inflicted in "Crutch". He acts as an informant for Sector Q, or more precisely Nolan. He was later captured by Numbuh 3.14 to be interrogated. During a teen assembly, the Mayhem Squad beat Mario to a near bloody pulp. Despite severe injuries, Mario proved to be a tough nut to break. He was later rescued by Sector Q and taken back to the moon base where they all were knocked out by Numbuh 501.
Mario later awoke tied up. After being freed, Numbuhs 91 and 99 would help Mario out of the room they were in and onto the M.A.T.O.R.O.. Mario would later take part in the final battle in the science fair, by revealing that he could stand (to which Nolan questioned), and held Merc at gun point.
Mario returned in the story "Ethics", finally being able to walk again. Nolan called Mario while he was getting ready to pick Merc up and go to a party. The next day, Nolan comes to Mario with the recommissioning device and recommissions Mario, so he can confirm his suspicions. After being recommissioned, Mario confirms Figure's possible identity and Nolan leaves.
Mario later appears in the story "When Dads Away", being asked to by Dustin to bring them food and refreshments. Mario is later tied to a wall by some of the party goers in a makeshift game of pin the tail on the donkey.
In Legend of the Eight Firstborn, Mario participates in the fight against the Brotherhood of Evil. He defeats Le Mime by shooting an imaginary gun at his own numb foot, and when Le Mime mimics this attack, he hurts his own foot with the "real" gun.
In the future, Edward runs the bookstore called The Q. Nolan also gave his son's middle name after Mario's surname, Ramsey. Dillon's shadow's name is also named Mario. In Operation: SCARY, Mario informs Nolan of vampire weaknesses, then later makes a sword of those weaknesses so Nolan can beat Dracula.
Mario appears in the story 'KND: Civil War' under his nickname 'Joker'. In this universe, however since the events of Ethics have never taken place, Mario is still condemned to his wheel chair and never regained his memories.
Mario later reappears in the story 'KND: Aggressive Tendencies' where he has regained the ability to walk and is currently the manager of a book store called 'The Q' and works along with Koda and Edward. Mario is also aware of Nolan's alter ego as Sandman.
Edward and Mario appear to be good friends.
Merc is a member of the Mayhem Squad. Mario taunted Merc at her attempts to break him. She seems to enjoy torturing Mario. Mario is now currently dating Merc.
Nolan and Mario became friends instantly after he helped Sector Q. Mario even risked his life for his new friend. Two years after his decommissioning, Mario still remains as a friend to Nolan. He also serves as Nolan's informant for everything going on within the teens.
Dillon and Mario always bicker and throw insults at one another, but in reality they are good friends. They always watch out for the other. Dillon was visibly shocked when his friend was going to be decommissioned.
- Although unaware of it, Mario was the one who coined the name 'Prospectors', giving Nolan the idea for what to call the soon to be Prospectors.
- Mario's theme song is 'Dare' by Stan Bush.