Who is the man thats always sitting beside the Pope?

and why does he always have this devilish grin? and why does pope sit in front of an upside down cross with this man to his left hand..kind of weird because jesus sits at Gods right hand. who is this dude and why the evil face? in revalations the kingdom with colors red and scarlet is where the antichrist sits. isnt that the colors of the vatican city?