They are mute characters, and possibly dwarves.
They appear to be identical twins and wear identical outfits: a red hat with a blue ribbon, a red tunic, white tights and black shoes. They both have a serious expression on their face.
They are seen removing the King's slippers before bed, and rolling up their sleeves when asked to escort Derek from the King's chamber. They carry the King's robe on special occasions (such as The Royal Ball). They have their own quarters accessible by two small doors outside the King's chambers.