City of Bones

I just recently started reading City of Bones by Cassandra Clare. The book so far has featured a somewhat realistic world with a fantasy twist to it. Demons and other monsters are proven real, and the main character, Clary, can see them. Most humans can not see them. Clary is attacked by a demon, as is her mother, and they are separated. Clary is taken with a demon hunter, Jace. Earlier in the book, she had witnessed Jace kill a demon. I found it interesting that she was not abducted when they found out she could see them. They had apparently considered it and it would have been a logical time in the plot to introduce her to the new world, but Cassandra Clare lets Clary go back to a normal life for a few days until she is attacked. In previous fantasy books I've read, the author has never hesitated to plunge the main character into the plot quickly. My only explanation is that she was trying to give the reader more background information on the history of Clary's mother's life. I only picked up from the reading that Clary's mom had something interesting about her for her to get attacked. I am assuming that Clary's mom also can see the demons and that is what the background information's purpose was used to set up.