Trista

Trista is a girl and a minor character in the series who met Greg and Rowley at the end of The Last Straw. They took her to the country club that the Jeffersons belonged to in Dog Days; within five minutes, however, she met a lifeguard, hung out with him for the rest of the time, and forgot all about Greg and Rowley. This causes Greg to disregard her. She has not been seen in the series ever since.

Trivia

 * Which state Trista moved from remains unknown, though in the online book, Greg notes down that Trista came from New Mexico.