Fear is a motif in the poem.
"A Narrow Fellow in the Grass" starts out with an image that seems to evoke the opposite of fear. The "fellow" in the first line hardly seems fearful, especially since the word "fellow" evokes a feeling of familiarity and a sense of ease. By calling the snake a "fellow," Dickinson almost gives it a personality. It seems far from the imposing, fearful creature the snake has traditionally been thought to embody.