 Before the writing of " S.R. 819 " , the writers for The X @-@ Files felt that the character of Walter Skinner was becoming too " expendable " . John Shiban , the writer of the episode , decided to re @-@ work Skinner back into the series ' mythology by crafting the episode around him . Mitch Pileggi had to endure long bouts of make @-@ up application , a process that he admitted he " hated " . The nanobots in the blood sample were designed on a computer and then rendered for the final footage . 
