As a npc. Search for ‘uboa’ on Youtube for reference.
Bonus points for creepy sounds and change of colours. (Not the npc but everything else. A simple colour filter could be a way to do it.)
It is from the highly interesting game ‘Yume Nikki.’ You should play it if you haven’t already.
If an npc is a little TOO much then see:
Edit: I would prefer a non-pixelated version. Reference: http://fc03.deviantart.net/fs28/f/2008/106/e/3/Uboa_by_chrono_fox.png