Ennis is the love interest of Firo Prochainezo in Baccano!. She is a homunculus created by Szilard using his cells and the cells of an abducted female. She is the latest in a group of homunculi Szilard created, and she is the only female. Although she was "born" without any knowledge, she eventually begins to experience emotions. Although Ennis hates Szilard, she obeys his every order because he is able to kill her with a thought. She betrays Szilard and gives Firo Prochainezo the necessary knowledge to destroy Szilard. She falls in love with Firo and marries him in the 1980s after developing her emotions for fifty years.