Claire has the whole geography-teaching scam figured out.[1]
Claire Little, usually referred to as "Little Claire" owing to her diminutive size as well as her surname, is a student at Griswald's Grammar School in the same year as the "mystery kids". She first appeared in "The Case of the Simple Soul". She is the daughter of the Tackleford fire chief, but was an arsonist (for which she was never caught and punished). She set fire to barns because she wanted to gain control of fire out of fear of her father dying in one, though by setting those fires she actually put firefighters including her father in more danger. She seems to have gotten back into fire-setting more recently after a difficult breakup.
When Charlotte Grote was moved into the same class as her in their second year (and away from the other mystery kids who were in the Latin class), she exclaimed, "I can't take... six years... sitting next to Little Claire...", but over time she became friends with her. By the time of "The Case of the Modern Men", she was hanging out with Claire quite a bit, while Shauna and Mildred had other activities occupying their time, and Charlotte and Claire also had in common that they were both hosting French exchange students (though the fact that these two French girls were bitter enemies of one another complicated things). Later, Charlotte was the one friend to comfort her after a painful breakup, and in the wake of the breakdown of the friendship between Charlotte and Shauna, Claire seems to be moving into the spot of Charlotte's best friend.
Claire was in a lengthy relationship with Colm O'Shaunessy, beginning with a passionate kiss, coming soon after Colm was released from incarceration after being falsely believed responsible for a series of barn fires (which the local Tackleford Troll also got accused of). She apparently falls for Colm during the intense speech he gives at the press conference that follows his release and during which he is presented with a pair of socks hand-knitted by Claire as means of recompensation for his wrongful detention at a psychiatric ward. Colm soon discovered that Claire herself was actually responsible for the fires, but didn't tell anybody about it and it didn't harm the relationship. This relationship ended abruptly years later when he announced an upcoming move to Ireland and that he was getting tired of her anyway. This put Claire in a state of misery she later got out of by getting a makeover from Jack's hairdresser father. Linton developed a crush on her and seemed to be getting together, but then got in a fight with Colm, who regretted letting Claire go, and when Claire tended to the injured Colm, Linton went off and kissed Blossom Cooper.
Claire speaks with a lisp, which gets more and less intense at different times, sometimes correlated with her stress level.
At one point she attempted to aid Desmond Fishman, when he was living on the street, but he didn't take well to her assistance. She persisted, however, eventually persuading Desmond's butler Fotheringay to assist her in improving Desmond's behaviour by the reinforcement technique of giving him tighter, more uncomfortable pants when he misbehaved. Later, along with Lottie, Claire ended up running Desmond's campaign for parliament, and during this campaign Erin Winters tried to inject a scandal by printing an article in the Tackleford Cormorant claiming that the two girls were born in rival town Wendlefield.
Following a 6 - 0 landslide vote by the mystery kids, Claire eventually became their official 7th member. (They needed her to break a tie concerning the question about how to proceed in the matter of Tim's Time Dad.)