It is generally acknowledged that Lu Xun’s collection of prose poems, Wild Grass (Yecao), is his epitomizing work. Among the numerous research on this work, it is rare to find studies that explicitly expound Zhou Zuoren’s relationship with Lu Xun and his effect upon the latter’s writing. This is probably because scholars seldom associate poetry with Zhou Zuoren, a writer famous for his prose and essays. In addition, the relationship between the two brothers broke up completely in 1923. Therefore, Zhou Zuoren does not appear to have played a significant role in the composition of Wild Grass in 1924. This essay attempts to explore the relationship between the two brothers from a new perspective, revolving the analysis around the “Shadow’s Leave-Taking” (Ying de gaobie) the most difficult and important work in Lu Xun’s collection of prose poems, Wild Grass.