Issues. We all have them in many forms. Some are contemporary. 'Can I pay the bills this month? Will my day job still be here next week?' and a rash of other problems facing us every day. Some have been with us since childhood such as relationships with parents, siblings and friends. Some we've added in our adult years with interactions between us and significant others and perhaps our careers.
We all have issues and deal with them in our own ways. But as writers, it's important our characters have issues. The most interesting protagonist has a history and it shouldn't be all silver spoons and rose beds. Past experiences mold people. These experiences may strengthen a person or instill them with their greatest weakness. Sometimes our characters are aware of the issues driving them and creating a great story for the reader. Perhaps our characters aren't aware of their motivations and the issues behind them. A writer can weave an complex tale and slowly reveal a character history. A character without issues, perfect and without fault, is boring.
Antagonist need a history too. They can't be totally evil. A great story has a complex bad guy with issues of his or her own.
Issues. Everyone has to have them, especially our characters. Did you ever read a book where the hero or heroine was too perfect? How about a bad guy too perfectly evil? Have you read a book where you've admired the weaving of a character's issues with the plot of the novel?