Heather Hills

Heather Hills is a teenager in Rodrick Heffley's grade. Greg Heffley has a big crush on her.

Rodrick Rules
In the second book she baby\sits Rowley while his parents were gone. She was later replaced by Leland. In the 2nd film she is shown as Rodrick's girlfriend at his party. She is also mentioned by Holly. Holly shows that Heather is a female version of Rodrick.

Dog Days
In Dog Days, Greg always tries to impress her, but she barely pays any attention to him. She has a younger sister, Holly Hills, who Greg also has a crush on. She is a lifeguard at the public pool in Dog Days, and Greg attends to her every whim while there, but she pays him no mind, except when a kid vomits.

Film series
Heather is only briefly mentioned in Diary of a Wimpy Kid: Rodrick Rules (film) and is described by Holly as a female equivilant of Rodrick.

She later appears in the third film as a love interest of Rodrick and the main antagonist, acting like a bigger jerk then Rodrick, being a steryotical self centered teenage girl. She first shows up to pick Holly from school, and when Rodrick tries to flirt with her, she runs over his foot. She naturally goes to the same Country Club as her family, getting a job there as a life gaurd. She acts rude to almost everyone, including her own parents, only thinking about her upcoming sweet sixteen and even ignores when Rodrick pretends to drown to get her attention. Greg manages to get her to hire Loaded Diper for her birthday, where there, it falls into ruins when she angirly reacts to Rodrick's rock cover of Justin Beiber's "Baby".

Trivia

 * In the online book, she is known as "Piper Matthews."
 * Why Heather was replaced as Rowley's babysitter is unknown, but uncharacteristically, in the online book, it states that she was fired for smoking outside Rowley's house after she had put him to bed.