Spite is a passive aggressive act. Instead of dealing with an issue head on, a person intentionally acts to annoy, irritate or frustrate the other person. Then when the other person reacts with the intended frustration or irritation they gloat with satisfaction at their destructive power and the other person's emotional outburst.
Spite is one of the most destructive behaviours. The individual enjoys the power and authority they feel for actively forcing another into weakness and turmoil. I think people learn this behaviour as kids when they are forced to "be nice" to a sibling or person who they believe doesn't deserve it. It's a way of secretly weilding power over another person yet still playing within the rules. "What? I didn't do anything Mom!" Spite is a destructive, not constructive, way to gain a sense of equalibrium and leverage a sense of authority over another.
So how do we curb it?
I think we have to deal with the perpetrators underlying feelings. We have to have the uncomfortable conversation and find out why the spiteful person feels as though they are in a comprising position. Then teach them alternative ways to deal with their emotions. And with the victim, we need to teach them alternative ways to manage their emotions. They need to know how to stand strong, weather the storm, brush off the debris and carry on. Because without a reaction the spiteful person gets no satisfaction.
So now, what are alternative, constructive ways of dealing with, and managing our emotions?