Fraternal
"Fraternal" refers to a bond or relationship that resembles that of brothers. It often describes the close ties and camaraderie found in groups or organizations, such as fraternal organizations like the Freemasons or Knights of Columbus. These groups typically promote fellowship, mutual support, and shared values among their members.
In a broader sense, "fraternal" can also apply to any relationship characterized by brotherly affection or solidarity. This term is often used in contexts like fraternal twins, which are siblings born at the same time but from separate eggs, highlighting the familial connection that exists between them.