The image is from Supernatural (I felt I recognized it) http://supernatural.wikia.com/wiki/Changeling

They have been talked about throughout history as being the replacements for human children who are stolen away by monsters. The children are usually taken underground, and fed on by the mother changeling. The changeling that replaces the child looks the same as the original child, but is evil, and otherwise acts differently. They feed off the mother of the child they have taken the form of. They are very protective of their food source and will let nothing separate them from it and will kill anyone who gets in their way. The mothers get fed on gradually and will last a few months before death, at which point the changelings move on to the next neighbourhood.

Although they act somewhat like children, the young are cold and do not seem right. As such, some mothers notice that it is not their child.