Can a character lie about who they are on the network/in person? Are they registered under whatever name they give or their true identity?

I ask since the Nogitsune is a dark spirit that's cruising around in a copy of Stiles' body. It's not the most popular of critters since it does tend to live on the ugly emotions/pain of others, it would lie and say it's Stiles and try to avoid meeting up with Derek. Anyone from its canon or those that can see spirits could easy call it out as a liar, but I'm asking about arrival and starting out.