She is the kind of girl that always likes to talk about fashion and how most people can be cool and rich like her all the time. Most of the time, she is sort of mean, sassy, and also judging others by the appearance of each person. But sometimes, when she feels guilty for something that she did wrong, she starts having a change of heart, in which she starts being nice and also supports people for whom she really cares about including Arnold.
Rhonda and Arnold have been good friends because of their feelings and understanding for each other. For instance, Arnold is always there to give advice or lend a helping hand to Rhonda whenever she's facing her problems in life, and like with nearly everyone else in Arnold's world, he sees the good in her and helps her find ways to bring it out. For Rhonda, she likes Arnold because of how cool he is and also by the way she likes to be nice to him for those time that they're doing something that they like to enjoy doing. It appears that they both have a strong liking for each other in person, which makes them feel good when it's just themselves.