After Theseion Solon's death, there was a panel of Eros holding a black bishop and destroying it. I have two explanations for this. Its either Eros sees Perion as evil (cause he gets in his way all the time) hence him representing Pel as a black bishop OR
Moving on, Perion's chess piece counterpart was revealed to be a white Bishop in episode 59. Given its name, a bishop symbolizes the Church which would make sense because Perion is the Cardinal. Bishops are known to be a close support to the King and Queen of the game
