Serial killers often have traumatic childhoods involving abusive or absent parents. They frequently show early signs such as torturing animals and having an interest in violence. While portrayed as villains, some serial killers in media are depicted as anti-heroes. Real serial killers are sometimes inspired by other notorious killers and combine elements of their crimes. The psychology of serial killers is complex, but they generally lack empathy, seek power over victims, and find killing sexually gratifying or thrilling.