How do your characters react to surprises of any kind? I know of people who loathe any kind of surprise and who prefer their lives to be on a nice steady basis. Characters can be like that. Surprises can change the course of someone's life for good or for ill and again this could and should be reflected in fiction.
What motivates "your people" to spring surprises on others? Out of a genuine desire to do good, stir up mischief, or to try to get the upper hand over someone? And do your stories leave your readers surprised (in a good way, wanting more of your stories!)? A lot of my flash fiction would be classed as twist in the tale so I have to make sure there really is a twist and one that is not unreasonable, based on the premise shown in the story. So do your surprises make sense and if the surprise was meant to be nice but the person reacts badly to it, how does the originator of the surprise react and what does this do to the relationship between the two characters? I expect there would be some good stories to be written there. Good luck!