While you could have him walking through life grabbing the mask of the person closest to himself and putting it on leaving both of them wearing the same mask this would represent the MC being a sociopath or a psychopath (depending on created or born that way). While this would show how he moves through life blending but not belonging the writer has to understand that his MC is a sociopath (not that there is anything wrong with that) and that this is still played out.
You could have the MC going through the world placing masks on people as commentary about the currently levels of politics-media-"human" functionality/autonomy but I'm not sure where you go from there without reaching into the plagiarism/cliche' bag.
You could shonen it up and have them fight/struggle with other characters for control of the emotional mob but you are in dark territory that most people do not like if you go there. On the upside, writing in the uncomfortable zone leads to less chance of just recycling other people's stuff and less chance of getting noticed when you do.