Mrs. Olinski lacks confidence. Crippled in an automobile accident, she has had to rebuild her life, both as an individual and as a teacher. Realizing that she needs help, the Souls unite to "give her a lift".
Noah is extremely egotistical. Nadia constantly takes him to task because he always has to be right. At first, he does not see why he has to write a thank you letter to his grandparents for having him stay with them in Florida; he thinks he was so much help, they should thank him. After reflecting on his experiences, however, he realizes the importance of "giving...(something) back".
Ethan is a loner who tries not to stand out. He learns to overcome his tendency to block others out when Julian befriends him on the bus.
Nadia is angry and resentful that her parents have gotten a divorce. She tends to indulge in self-pity, shutting out the attempts of others to help her. Nadia's experience with the turtles helps her understand that everyone, at all stages of life, needs "a lift" sometimes, and that it is as important to be receptive to the help of others as it is to give it.
Julian's character flaw is the hardest to pinpoint, since he has already learned the lesson of kindness and the importance of sharing it with others. I think he must have had somewhat of a temper, however, and a tendency to want to seek revenge. He overcomes this temptation when he decides not to let Hamilton Knapp's stunt with the poisoned dog treats backfire on his dog, but he cannot stop himself from exposing the boy's devious plot to his mother.