The protagonist of Rules by Cynthia Lord is twelve-year-old Catherine, and her job is to be a caretaker for her eight-year-old brother, David. School has ended and summer has begun, and things should go pretty well for both of them. What we learn, though, is that taking care of Davis is a full-time job be cause he is autistic.
In the exposition, we also meet Kristi, the girl who moves in next door; Ryan, a mean boy; and Jason Morehouse, a paraplegic boy who can only express himself through the word cards his mother has written out for him. The conflict, we discover, is Catherine's resentment at having to watch her brother so often; he is treated, she thinks, better than she is, and even knowing that David cannot help being the way he is does not make Catherine feel better.
Catherine has so longed for a friend with whom she can do things during the summer, since her friend Melissa goes away every summer. Catherine hopes this summer will be different because Kristi is here:
This year'll be different, though. The girl next door and I can do all my favorite summer things together: swimming at the pond, watching TV, and riding bikes. We could even send midnight messages from our windows, using flashlights and Morse code, like next-door-friends do in books. And the best part, David won't have to come since Mom won't have to drive me and pick me up.
Unfortunately, things do not happen as she ideally imagined.
The inciting action is when Catherine finally meets Kristi. From there, a series of events leads to the climax/crisis/turning point in the novel. Unfortunately, Ryan is with Kristi and this spells nothing but trouble and heartache for Catherine as her relationship with Kristi develops. On a positive note, Catherine begins to spend more time with Jason.
In the midst of making rules for her brother, Catherine realizes how confining it must be to be limited only to the words on a card--and even then, only to the words which Jason's mother has given him. Catherine adds words like "awesome" and "stinks a big one," allowing her friend to express himself more completely (something she has not really learned yet to do, as she has not been able to tell her parents how much she resents having to take care of David so much of the time).
When she discovers Jason's dream is to be able to run, she simulates that experience by pushing him as fast as she dares, and their friendship continues to grow. Jason loves Catherine's drawings, and it becoming clear that Jason is developing feelings for Catherine. She and Kristi make some posters for the dance, and Kristi wonders if Catherine would consider going to the dance with Jason. All Catherine says is "maybe."
Jason invites Catherine to his birthday party and includes both David and Kristi in the invitation. Catherine, however, is selfish and rather jealous and does not want them to attend. She buys Jason a birthday gift: a guitar. David is at the party and of course she has to keep a close eye on him. Kristi does not come.
The moment where everything changes (climax) happens at Jason's party. Using his word book, he asks Catherine to go to the dance with him.