WordNet
n. the friendship characteristic of blood brothers
Usage examples of "blood brotherhood".
Liet Kynes saw little of his father during his earliest childhood Many of the duties that would ordinarily have been filled by his father had been taken over by Stilgar a Fremen fifteen years Liet Kynes senior whom Pardot Kynes had seen joined to his son in blood brotherhood in 101 j8 Raised with the rest of the sietch children he was taught the ways of bled and sietch, palmary and desert He learned Fremen history as related by the Sayyadina water discipline and customs, and the fanatic hatred the Fremen had possessed for all those of House Harkonnen since the day Beast Rabban had been gi\en jurisdiction over Arrakis in 10162 To anyone not knowing his parentage, the boy would have seemed like any other Fremen youngster, the product of generations of life on the desert planet .
Alcoholics Anonymous gives you an extended family that's very close to a blood brotherhood, because everybody has endured the same catastrophe.
The inner surface of the hand still shows pressure marks made by the self same knife, with which Walter Matern and Eduard Amsel, when they were eight years old and intent on blood brotherhood, had scored their arms, because Kornelius Kabrun, who had been in German Southwest Africa and knew about Hottentots, had told them how it was done.
Every clan of the eastern tribes had a feud with somebody waiting to flare up again, and everyone was related to everyone else by descent or marriage or blood brotherhood, so a single killing could sprawl out into an uncontrollable free-for-all of ambushes and lethal brawls like a sweater unraveling from a single tug.
It's a sort of brotherhood, a blood brotherhood, but that's not exactly it, either, but it's as close as I can come.