BRAINTREE (CBS) – A Braintree second grader is so devoted to her little brother she wrote him a book. Marin and Henry share a special bond and at eight years old, she is already looking out for him.

“She loves her brother, and it’s been hard for her,” their father Ross MacDonald said.

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Henry is two years old and was recently diagnosed with autism. Soon after, Marin decided to create something to bring him joy and comfort.

Henry and Marin (WBZ-TV)

“Instead of like carrying around a stuffed animal or a blanket around or like a lovie, he carries this book around,” Marin said.

Their mom, Alison, says Marin came up with the idea to make a book for Henry and wrote it about his favorite thing: dinosaurs.

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“She brought it over to her brother and said ‘I have a surprise Henry, I wrote a book for you.’ And she had about maybe eight drawings of dinosaurs that she had come up with,” Alison MacDonald said.

With the help of her mom and a few others, Marin wrote the story and even drew the characters for her new book called “Ninos Dinos: A Book Dedicated To All Kids With Autism.” The family is donating all the proceeds from the book to several autism charities.

Henry and Marin (WBZ-TV)

“As our daughter has shown there’s not just self-interest, it’s about helping others because that’s the only way the world can go round, and anything we can do to make a difference we want to do,” Ross said.

So what does Henry think of the book? According to the author, they enjoy the book together.

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“He’ll sometimes want me to read it to him, so that’s what I do for him,” Marin said.