In the real world, each of us have our set of friends. They come from different backgrounds, might have a different perspective in life, but ultimately we all have something in common that bonds us
In my case those who are close to me are treated like siblings, knows me inside out, and my partners in crime. We are there for each other in times of happiness and of need. We can’t deny the fact that there are friends who are closer to us compared to others – who we call ‘best friends‘.
In the military (US Army in particular), it’s the same thing, but they’re called ‘battle buddy‘.