If you join a wall and an architectural column, and the wall has a coarse-scale fill pattern defined, the joined column assumes that pattern.
See Wall Type Properties. This behavior is evident in coarse-scale plan and section views. The section view plane must cut through the joined face of the 2 elements.
Wall and column joined (column assumes the fill pattern of the wall)
Note: Structural columns do not assume the walls fill pattern, even when joined.