Now, I started thinking about this because of the boots. But the deeper you go the more similarities you see. First of all the fight between Yang and Mercury could allude to the fight Puss had against the ogre king. He knew he was going to lose so he used trickery and lies and the ogre's own strength against itself. Mercury tricked Yang into breaking his 'leg' to make him win. He also was shown in the books as a follower. The cat listened to his master's wishes and went to make them come true. Mercury is shown to constantly follow orders, but to also act on inititive, as shown when he tested Pyrrha in the school.