Fudge has Asperger's Syndrome.
That explains why he has a rather peculiar personality, and he has great interests in certain objects (i.e birds, money, etc.). He also has annoyingly quirky habits, such as counting 200 Cheerios before eating them. He's also creative and is above-average intellectually for his age, a common trait of children with Asperger's Syndrome (now considered a form of Autism Spectrum Disorder that doesn't affect language development and goes hand in hand with above-average intelligence.- It's likely that Fudge's friend in Superfudge, Daniel Manheim, may have Asperger's Syndrome as well. He introduces himself with detail in the same way each time he meets someone new, also shows a great interest in birds (this includes talking about habits and history of myna birds), and also has the habit of asking someone "Wanna make somethin' of it?" in a tough-guy accent. He's also picky about certain things, especially foods, and frequently mentions so. note
Anne goes through postpartum depression after Tootsie's birth.
At one point, Peter comes home from school to find his mother lying on her bed with her hands over her face, having just put Tootsie down for a nap. Later she breaks down crying in front of Peter and confesses how tired and overwhelmed she feels from all the work she has to do. This might be just the ordinary stress of having a new baby, made worse by Fudge's regressing into babyish behavior and wetting his pants and bed again due to Infant Sibling Jealousy, but it might also be deeper and more clinical than that. Fortunately, her husband and mother give her the support she needs, and after a few months she recovers.