First, you should always consider the past, if there were some conflicts in past, there are more chances that the person could harm you anyways some day. Apart from that, the person could try to hamper your image in front of others by saying something bad about you but in sugar-coated manner (examples- you know X is such a foodie that she even doesn't care about her chubby tummy. It was a humorous way but impacted your image. The other person get to know that you are foodie and eat all the time). The person could try to put you in trouble every now and then possible, but the troubles like there are some guest coming, so your sister says mumma X cooks so well, let her cook this-this and i will prepare the salad. So these are some of the behaviors where spitefulness is evident. Hope it help.