A brother from different parents

After watching Prison Break, nothing struck me much rather than Michael Scotfield and Lincoln Burrows not being brothers and yet loving each other with their lives. I have also heard Jackie Chan saying in one of his movies that his friend was his brother from another mother/parents. Can some one really love a friend(s) more than their blood related brothers or at least as much as their own brothers?
There is a written verse in the book of proverbs that there is a friend closer than a brother. And a neighbor is better than a brother living far away. So, my point is where do we find these type of friends on whom we can really depend on? In the song 'A friend like You', the writer found a friend who is not just someone funny or cool, a friend who he can really depend on. Can this type of friend be a brother from different parents?
Some people may meet this type of friends in schools and colleges where they don't have any family. I too have met some friends much closer than a brother, friends that can help me when my brother is not available, a friend that can hear me when my brother can't hear me. I called them my brothers from different parents.
There are no boundaries in making friends, no religion can separate friends, no caste or race can separate friends. It is often said that friendship is a gift from God and it is a ship that never sinks.