Relationship Through Doing

As a child and young adult, I found it hard to make friends. I had no idea how other people did this. Watching my son fall in easily with other children, it’s still something of a mystery. What is the process by which people decide that they will be friends with each other? I’ve never really sought casual acquaintance, although I can be passably friendly because I find other people inherently interesting. But it normally takes me years to really bond with a person.