Victims of Stockholm syndrome develop compassion and loyalty toward their captors.
Here's a great article: http://counsellingresource.com/lib/therapy/self-help/stockholm/
You can get an understanding of the psychology behind this.
It can be found in many family, romantic, and interpersonal relationships.
The syndrome was coined "Stockholm syndrome," after 4 people who were taken hostage at a bank in Stockholm in 1973 appeared to have "bonded" with their captors. Upon rescue, the hostages feared the law enforcement. One woman later became engaged to one of the criminals and another developed a legal defense fund to help in their legal defense fees.