Her Royal Duchess Diamond Persnickety, the First, Last and Only (Thank Goodness) ("Duchess" for short) is an imaginary friend; who is a recurring character and one of the main antagonists of the series She speaks with a German accent. This imaginary friend is a scheming, pompous, negative, rude, arrogant Picasso-like pain in the neck, who is actually two-dimensional when she turns her head or body. She's considered a "high-maintenance" friend, not wanting to do anything for herself, and is so lazy that she needs somebody to open her eyelids when she wakes up. The residents seem to follow her commands because she is both able and willing to scream incredibly loudly for an indefinete period of time without rest unless she gets what she wants. Despite her desire to leave, Duchess insult's almost everyone who tries to adopt her. showing that while she badly wants to leave she doesn't want to live in any less pampered lifestyle she would be forced to give up if she went home with a normal family (in other words, she wants to be adopted by a rich family). Everyone else desires her to leave very badly however, so much so that Mr Herriman spends the entire budget for advertising adoption on her, even saying that he will pay a family to take her.

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