They talk about their personal experience of being bothered/bullied for something they have that is considered ugly by society. Therefore, having a common experience that feels unique to us can build a friendship.
They share their philosophy about life and how people behave with each other. While their perspectives do not always match, talking about beliefs itself is something that can bring people closer.
They challenge each other and do not behave in a polite manner with each other. Being who we really are and saying how we feel can build meaningful connections.