Duncan is a troublemaker who wants to escape the daycare at all costs. He also loves to make mischief, either by teasing other students or encouraging them to do naughty things. Like his older self however, Duncan is not entirely a bad person, helping his friends at times.
In Venthalla, Duncan formulates a plan to break into Chef's office to take back Owen's Uber Ball, masking his true plan to escape the daycare. Having retrieved Chef's glass eye, Duncan forms a team consisting of himself, Izzy (who memorized the code on the locker), Owen, Jude, Harold and Courtney (who he correctly deduced will expose them) to enter the Chef's office via the ventilation system and leaves Noah in the class to distract Chef. After the team retrieve their toys, Duncan abandons them and make it to the roof. As he tries to scale down the building, he accidentally tied himself with the toilet paper he is using and is caught by Chef.
In Duck Duck Juice, Duncan attempts to escape the daycare again, this time by creating a makeshift explosive using modelling clay and pop candy. Before he can carries out his plan however, he is pulled back to class by Izzy. After Izzy and Jude drank finish Chef's Rainbow Juice, Duncan volunteers to leave the daycare to buy another cup though Courtney tags along. Duncan actually plans to take advantage of this to skip school but Courtney handcuffs him to herself while they are on the way back. At the end of the episode, Izzy uses Duncan's clay to make a rabbit and sprinkles water at it. Duncan quickly knocks the clay bunny away from Izzy but it landed beneath Chef and explodes.
In Germ Factory, Duncan finds out that Leshawna is absent due to a cold and comes up with a plan to get sick as well in order to skip school. Rallying the other kids to his cause, Duncan's plan involves licking any contaminated surfaces in order to catch germs. The plan works and every kid suffers from bouts of vomiting and diarrhea. Forced to rest in bed the next day, Duncan admits that his latest plan is the worst plan ever.