YMMV / Penny And Aggie Missing Person Cyndi And Charlotte
Base Breaker: Right up until the strip that confirmed Cyndi's Complete Monster nature, there was considerable, even heated, debate within the fandom as to whether she or Charlotte was the worse person.
The story shows her manipulating Charlotte into suicide not simply to save her life, but for her own amusement. In addition, we are shown an extract from her private journal in which she outlines her plans to manipulate Daphne and Meg, among others, into killing themselves. Finally, Cyndi had earlier been shown (albeit to a subtler degree) manipulating Michelle into developing an eating disorder; that this was her intention is confirmed by Cyndi estimating later in her journal that Michelle would've been dead in about two weeks if "the Peacies" hadn't stepped in.
No justification is ever offered for her misdeeds, other than mental illness (Campbell has said on the forum only that she has elements of antisocial personality disorder and narcissistic personality disorder [but without being a textbook case of either], as well as traces of the psychotic delusion that the universe exists solely for her benefit).
Cyndi never performs a selfless act and never shows remorse for her misdeeds, whether they be feigning sexual or romantic interest in others, helping to break up a relationship, or manipulating others into killing themselves. What's more, she derives Better Than Sexpleasure from her actions. The closest Cyndi comes to possessing a relatable human trait is when she reflects on how her inability to relate to others makes her isolated and somewhat lonely, hence her crush on Sara-as-Lady-Macbeth. However, that loneliness never prompts her even to try changing her ways.
Due to the nature of her mental illness—a complete lack of empathy, conscience and remorse—a Heel–Face Turn, even a Redemption Equals Death, would be wholly unrealistic. Thus, her fate in the end is to suffer assault, confinement, torture and potential murder at the hands of a character too much of a wild card for her to anticipate, and as an indirect result of that, to see the testimony of her own journal condemn her to involuntary psychiatric commitment and thus removal from the story.
Creator Breakdown: When a reader asked Campbell whether it had distressed him to get inside Cyndi's mind and think like a person with antisocial behaviour patterns, he stated that it was disturbing to get into both her and Charlotte's heads and that it made him "a neurotic mess" at times. He also revealed that he based the toolshed on the one in his parents' yard, and as a result developed a phobia of it.
Memetic Mutation: "Hee." Although Cyndi's signature sadistic giggle had appeared a few times before, its appearance at the moment of Charlotte's suicide attempt solidified its association with Cyndi, such that it appeared often in Fan Fiction, and became an in-joke on the forum (e.g., lampshading one's avoidance of typing a single "Hee" in a post lest it give the appearance of Cyndi having written it). Campbell himself said that he nearly had Daphne say "Hee" in this later strip, before realizing how readers might take that, whereupon he changed it to "Heh."