...I present the jester.
This lovely idiot could come with your first baron, there to entertain him and his lovely wife (yes, I'm using sexist generalizations for the sake of simplicity. Nyah). He is simply referred to as a "Fool", and will do nothing useful aside from maybe giving happy thoughts to the people he interacts with (or not, depending on their personality).
As the barony upgrades to a county, the fool becomes a "Jester". Really just a name change, since he does the same thing. When the county turns into a duchy, he becomes a "Court Jester". With the arrival of the king, he becomes a "Royal Jester". Either that, or he keeps the title of court jester. Room requirements may or may not be subject to change. Either way, he expects a free meal and a relatively comfortable room, but not much in the way of luxuries (mandates).
Heavily dyed clothing might be nice to see, but could be difficult to put in (I really don't know what I'm talking about).
So essentially it's a sociable philosopher who plays the part of a portable comedian. He could be helpful/hurtful by relaxing a noble who's angry after a failed mandate and becoming a "tantrum bomb" by making lots of friends within the fort (I think that just about every aspect of Dwarf Fortress should have the ability to both help and hurt the player). Or he could just be another useless hanger-on like the advisor and philosopher.
Comments, anyone?