In "Day of the Only Child!", Duey invents a holiday in which he and his brothers pretend to be only children. Louie uses this as an opportunity to meet Doofus, the richest kid in Duckburg. Meanwhile, Huey is forced to attend the Junior Woodchucks three-man cookout alone while Duey enacts his own talk show at McDuck Manor.
Upon arriving at Doofus' mansion, Louie is brought into his large, toy-filled playroom. Doofus introduces himself by gifting Louie with a "friend present" - a bracelet. Louie's day goes as well as he planned as he enjoys all the amenities Doofus has to offer. They eventually arrive in the treasure room where Doofus wrecks several valuable, priceless objects. Louie figures that 'real wealth' is being able to do whatever you want because nobody can stop you. He joins Doofus in the destruction, which abruptly ends when Louie almost desecrates a portrait of Doofus' late grandmother Frances (or "Gummeemama" as he calls her). Doofus goes crazy with rage and Louie quickly discovers his servants are really his parents. It is revealed that Doofus started out as a sweet and loving kid, which all changed when his grandmother passed away and he inherited her fortune, corrupting him into what he is now.
Louie attempts to escape, only to find out that his bracelet is a floor magnet which keeps him stuck, and that he was actually Doofus' friend present. Being held hostage, Louie tries to get Doofus' parents to help him, but is ratted out by his father. Doofus proceeds to punish Louie in an unknown manner using an umbrella and a bag of walnuts. Huey and the Beagle Boys suddenly crash into the room and find themselves in the situation as well. Once Dewey shows up with a security drone, he and his brothers decide to bond again in order to defeat Doofus and the Beagles.
Doofus displays an unusual, quirky disposition and a tepid personality. However, he is fiercely protective towards his late grandmother and loses his temper when things don't go his way. As mentioned by Louie, he only mingles with other wealthy heirs. As he later discovers, Doofus is possessive, insane, and spoiled rotten, a result of being too young to know how to handle his grandmother's fortune responsibly.
Like his original counterpart, Doofus is a rotund white duck with glasses. However, he now has a combover haircut, a fancy suit, and tan pants with a pocket chain.
- Doofus' change from his previous version is due to the fact that he was one of the few things the creators didn't like about the original DuckTales TV series (mostly stemmed by jokes that are considered too mean-spirited for today's standards). He is also confirmed to return in future episodes.
- Twilight's Anthony Fremont served as major inspiration for Doofus' character.
Television, Comics & Video Games