Basically the same thing
as Soul Sister, just referring to a guy instead.
Soul: The
immaterial part of a person; the actuating cause of an individual life.
Brother: A male person who has the same parents as another person.
Soul Brother: Someone who fully understands you. Like a soul mate, but not someone you want to marry and
make babies with. The brother of your soul.
Dude1:
Brah! Why is it, that we like all of the same things,
hate all of the same things, and have pretty much EVERYTHING in common?
Dude2: Because Brah, we're Soul
Brothers.