road-brother

Someone you meet in life that you grow to love as you would your own brother. Though you may put physical distance between you and them, you still live with them in your heart and mind as do they.

The people that will sit with you on a porch in the summer heat and drink with when you're body and mind are old; when you look them in the eyes you see each other as though you are still youthful, your smile without it's many creases, and your hand, arm, and shoulder still capable of bearing their weight.

An old friend, in a world where you make less old friends as you grow older.

(not to be confused with motorbike-club cultural concept of the same name)

John Smith: I met the guy in high school, we meet whenever we can. I love the guy.
Satoshi Nakamoto: That makes him your road-brother.
John Smith: Yeah, he's my road-brother, till the day we die.