Works of art that express a fearful/anxious tone might depict characters that are ill-at-ease, frightened, or terrified. Beyond representation, stylistic elements such as darker values with flashes of strong color, tentative/erratic paint application, and/or shaky scratched-in lines might contribute to a fearful/anxious feeling.
An artist might impart a fearful/anxious tone to a piece due to his or her own emotional state, or the artist might choose to evoke this tone as a reflection of the characters being portrayed. A fearful/anxious tone might also be adopted to suit a piece meant for a setting or purpose that demands the expression of anxiety.
Featured: The Scream by Edvard Munch.