One common characteristic is dishonesty. They might lie about their qualifications or past experiences. Another is a lack of genuine care for the children. Instead of nurturing, they may be neglectful or even cruel.
An 'evil nanny based on true story' can be a complex and tragic situation. It could start with the nanny seeming normal and trustworthy at first. But then, over time, strange things start to happen. She might isolate the children from their parents, or show signs of extreme jealousy towards the family's relationship. There have been real - life cases where nannies have caused long - term harm to the children, leaving emotional scars that are hard to heal. This kind of situation makes it really important for families to do thorough background checks when hiring a nanny.