This link is really focused on protecting children from predators who would groom them for abuse, but it is very similar to the way a narcissist grooms a victim. I found that I recognized situations where my ex narcopath did most of these things to me during the two years he groomed me before he moved in for the kill. This includes steps like: pushing boundaries, building trust with fake kinship, sharing secrets/asking for secrecy, and blaming the victim–making them feel guilty for allowing things to continue. I think this link gives some good information both for adults and kids.
Teaching Kids to Recognize Grooming