Diggle: You know I spent 27 years of my life in Starling City and the next 5 in Afghanistan. You want to know what I learned?
Oliver: There’s no place like home?
Diggle: No, just the opposite. Home is a battlefield. Back home they’re all trying to get you. To get you to open up. To get you to be someone you’re not sure you are anymore.
This expresses the backwardness anyone who has lived overseas or experienced trauma to some extent feels when returning home. How hard it is to talk to others when you are a different person from who they remember (or want you to be). It does a good job of showing how much is left unsaid…how much someone returning from overseas, or a trauma, or some sort of generally comprehensible event struggles in sharing their story or being part of “normal conversation.”