He was blood brother to my father, and cousin to my heroic uncles.
But since you've struck me, I'd do it if you were her own blood brother.
Toby took me up there, and they treated me as if I was their own blood brother.
Blood brother to the two kittens on the floor, Frosty was a third bigger than they.
They will do him no harm if he is willing to be their "blood brother."