Rob has appeared estranged from his famous family in recent months, reported Femalefirst.
"Rob was approached to do a tell-all book and he's recently signed a deal. He plans to claim that Kim sometimes uses her daughter North to promote Kanye West's tour and that her marriage is partly based on money and publicity.
"He wants to show how fame has changed and tainted the family over the years. They were a traditional church-going family who were very close and put each other's welfare first, but now he says they often row and everyone's falling apart in their own way," a source said.