Isabel Vinh is a classmate of Wade's at Teras Elementary, where she excels in math and history but struggles in science. Unless she focuses on staying in (or rather above) her seat, she tends to drift across the room during class, and has to be reminded by Mrs. Furk to return to her desk.
Isabel likes flying around the Terrace looking for dropped or salvageable objects, which she then gathers in order to trade them for other objects more valuable to her. These objects she in turn intends to trade for still better goods; she says she's hoping to trade up to the ultimate prize... she doesn't know what that prize is, but she'll know it when she sees it.
Isabel likes to hang out at Sally's Sundries, admiring Salmonella Wetherwood's business instincts and hoping to learn from her. The affection is more mutual than Salmonella would admit, and she often makes trades with the girl that are much to Isabel's advantage, sympathizing with and hoping to encourage her entrepreneurial spirit.