While the novel focuses mostly on the usual challenges a teenager might face - dealing with parents, fitting in, peer pressure and such - Rowell's characters also face some harder decisions and situations. There is no happy perfect ending but instead the novel leaves the reader with a bittersweet message of hope.
Park tries very hard to fit in, and has achieved that status in high school where he isn't popular, but he isn't picked on too much either. Given the community he lives in, he also represents a rather unique experience - he is half Korean since his parents, who are very much still in love, met while his father was overseas in the military. Park is hesitant to befriend Eleanor because he works hard enough to blend in, and talking to the odd redhead won't help him, but slowly they begin to talk, and a friendship develops.
Rowell, however, knows how to create characters. They aren't perfect, though they try hard to do the right thing, and they are so easy to relate to because even if their experiences are different from the readers' experiences, just about everyone can understand the feelings they are facing. Eleanor is the new girl in her community, and she sticks out. She appears to have developed quickly, and just feels like she takes up more space than she should. She also struggles with family problems, having lived apart from her mom and siblings for the last year due to her strong disagreements with her step-father. Having finally been allowed back home, Eleanor has to tread very lightly as she adjusts to the changed relationships in the house and gets to know her siblings again.