What are some controversial topics to talk about with your partner to deepen your bond?

We want to deepen our connection. What are some potentially controversial but important topics (politics, deep fears, past regrets) that, if discussed respectfully, can significantly strengthen a bond?

Talk about money and debt, what you each consider cheating, and whether or not you want kids. These are the things that actually break people up, not some abstract political debate. Trust me, you want to know the answers to these now.