Watching my kids, I have to say there is nothing like family for figuring out your weak spots and poking at them. I don’t think that it is meant in a malicious or evil way, it just happens. There are those that do pick on others just to see the reaction–kind of like picking on the kid in school that always cries when teased–but most people aren’t like that.
But I will say that family dynamics are some of the most complex and interesting. We don’t have the people within our family by choice. In a larger context, some wouldn’t choose family members for friends. But they are family. I’m one of those that believe that family supersedes everything. That family should stick together and support one another.
That said, family conflict makes for one of the greatest dynamics within storytelling. Because we know our brothers and/or sisters better than anyone, we know what buttons to push to make them angry. There exists jealousy (often unacknowledged) and sibling rivalry.
So for today’s prompt, does your main character have siblings? Brothers? Sisters? Both? How do they interact with them? Do they strive for one parent’s approval, thinking someone else has more attention? If so, what kind of behaviour do they exhibit as they try to receive what they feel is lacking? Does a sibling phone in the middle of something stressful because they need support (financial, emotional or something else). How does your character relate to their parents?
At least my kids are grown and I don’t have to physically pry them apart any more.