my brother, my neighbor, my friend, and an albacore

It is a fortunate person indeed who finds a circle of friends with whom they can share much of their life. I often wonder exactly what draws people together as friends...particularly when they have disparate interests. Sure, there can be some distinctions...but there should be some similarities.
When I was growing up I had 5 other kids that lived on our block...and I was friends with all of them. Some of us interacted by playing sports, others by playing pool, foosball, video games, board games, and other activities. We rode bikes for hours. We went fishing and to the park. We DID stuff together.
I had other friends I knew through church. Again...most of the things one of us did, we all did. Now that I am middle aged, I have taken to reexamining the nature of my friends and friendships.
Most of my friends have held that status for something like 25 to 30 years. Of my inner circle of friends, Alan holds the status of least length, clocking in at a mere 21 years, give or take a couple months. Those friendships stay true despite major changes in life.
Kyle, Billy and Alan all got married and had kids...Billy had multiple kids. Billy moved halfway across the country. Kyle lives nearly an hour away. Alan lives really close, but we both have hectic schedules that preclude doing much together. So the things that drew us together no longer exist, yet the state of friendship continues to exist. What holds that thread?
By the same token, what is it about family that encourages love and tenacity in maintaining good feelings for one other with a tenacity that sometimes borders on stupidity? We can talk about the mystical ties of "blood" and "ancestry" but the truth is...there are a lot of people out there who don't really know who is their blood relative. Adoptions, multiple marriages, multiple kids outside of marriage, the hot button topic of what constitues a family, and similar issues have clouded the truths of family.
By many measures it is crazy that my brother Kenneth and I are friends. We are very alike...hot-tempered, hard-headed, always right, and very, very opinionated. We also bring out a level of competitiveness towards each other that I do not see anywhere else.
We listen to different music, eat different foods, prefer different kinds of movies, videogames, and other recreational activities. I am a sports playing fanatic...or was until I destroyed my foot...whereas he prefers playing computer and video games. In short, there is very little to recommend friendship for us, yet we are very close indeed.
What are the factors in initiating, developing, and maintaining friendship, whether with family, neighbors, classmates, coworkers, or people we encounter elsewhere?
The real key is


. At least, that is how I see it. And I am sure I am right. Of course, I also think using invisible ink on a website is a good idea, so I could be wrong. And sadly...I thought that was funny. I think I shall go make dinner now.