The reason they called him "little brother Gu Che" was that he seemed so much like a little brother, especially in front of Qinghe, where he was incredibly well-behaved and listened to everything she said. It was said that he was only a few months older than Qinghe, but whenever they were together, it always felt more like Qinghe was the older sister.
So, when the others spoke to Qinghe about Gu Che, they always referred to him as "your little brother." Qinghe was especially kind to Gu Che, and Nalan Xue, who had a strong sense of loyalty, immediately rushed forward when she saw Gu Che surrounded, thinking that if Gu Che was hurt, Qinghe would be heartbroken to death.
