The spirit of the story was based on an anecdote Ward was told by a friend. A girl they knew, stranded in London with no money, used a dating app to find a place to stay. She slept with the man, stealing money for a taxi from his wallet the next morning. It was this ruthlessness and calculation in a female character which inspired 'Erica'.
The six shots fired by Ward's gun are reference to 'Six Shooter', a short by Martin McDonagh, of which Ward is a huge admirer