Bonnie is a brunette of average height with shoulder-length hair in a shag cut, teal eyes, a slender but curvaceous figure, and may be around 105-lb as stated by Kim when she and Bonnie were bonded together due to the effects of an invention by Professor Dementor. However that could just have been an estimation on Kim's part.
Bonnie usually comes off as very mean, rude, and snobby with a dismissive, cold attitude, and a superiority complex toward Kim, Ron Stoppable, their friends, and people in general, whom she considers to be beneath her. But while bonded to Kim's hip for a short time, it was strongly implied that Bonnie's sour disposition stems from her two older sisters, Connie and Lonnie, always being mean to her.
She generally avoids hard work. Although she did once put a lot of effort into usurping Kim as the Middleton High cheerleading captain while Kim was distracted with a mission. However, after Bonnie did gain the position, with the surprise help of Kim adding her vote and support to Bonnie, Kim explained that the hard work was only just beginning. After hearing that and realizing the responsibilities of actually being the captain of the squad, Bonnie started having second thoughts about it and presumably gave the position back to Kim sometime within two weeks or so.
Bonnie is also not above cheating to achieve her goals, such as rigging her senior year Homecoming-vote to become Queen, a result which could only enhance her standing on the proverbial "food chain", if not take her to the top.
Bonnie and Kim have been archrivals since at least middle school. While it is unknown how long she has actually known Kim, she knew her long enough prior to when Kim first tried out for cheerleading in middle school to have given her the nickname "Tin Teeth", due to Kim having braces. It was revealed during her senior year at Homecoming that she has known Ron almost at least as long as Kim knew him, as Bonnie had been calling him cruel names from Kindergarten to 12th-grade. Apparently she stepped up her level of disdain for him as Ron remarked when he was a millionaire that she had been mean and abusive to him since middle school.
Bonnie was very much concerned about the proverbial "food chain" at their high school and angled to keep her position on it by saving seats at lunch for the even more popular senior, Amelia, and by dating Brick Flagg, the then star quarterback of the Middleton High football team as that was considered a status symbol. A tactic which apparently worked as Bonnie was one of the only lower class students seen as able to sit at the senior lunch tables.
Nonetheless, Bonnie felt challenged by Kim's general popularity as well as her being the school cheerleading captain, the latter of which Bonnie coveted and managed to gain before eventually giving it back to Kim. Since then Bonnie was never nearly as vocal about replacing Kim as the captain. However she still angled to have prominent positions in routines; ever ready to step in whenever Kim might miss her mark in a layout, such as taking top of the pyramid at a Cheer Camp demonstration. Otherwise, Bonnie seems to consider it humiliating to be "second fiddle" to anyone for anything.
The rivalry between Bonnie and Tracy is no different than Kim and Bonnie. After failing High School in Middleton, Bonnie's parents announced to her, that after Graduation they were moving to the next town over(Bellwood). Seeing how she failed her senior year. Bonnie's parents enrolled her in Bellwood High where she soon met Tracy and her friends. Since the day they competed for spots on the cheerleading(which they both made and Tracy being Captian just like Kim was), Bonnie and Tracy had been bitter rivals since then. There had been numerous times when Bonnie would just make Tracy angry by kissing Seamus in front of her stating she likes British boys.
- Bonnie and Tracy seem to be at it each other with everything especially when it comes to Talent Shows and non-cheerleading sports(Softball, Tennis, etc.). This is stated in "MCF: The Isle of Music and Dreams".
- Bonnie is aware of the fact that Tracy is a princess and found her parents. Though despite the status, she still treats her cruelly. This is stated in "Isle of Music and Dreams."
- It is unknown if Bonnie is friends with Tricia. Though if they were it would be a mutual relationship.
- Bonnie's personality in the TV show and in MCF fanfics doesn't appear to be any different.