The word 弟兄 is formed by combining two characters, each representing a specific familial role: 弟 (younger brother) and 兄 (older brother). By joining them, the word doesn't merely list two separate individuals but creates a new, unified concept meaning "brothers". This formation conceptually merges the two distinct roles into a single collective term, emphasizing the bonded relationship and the group as a whole rather than the individual positions within it. The sequence of the characters itself may subtly reflect a natural or respectful order, but the core formation is one of conceptual fusion into a collective unit.