The query “why did Vergo have Law’s heart” refers to a significant plot point in the One Piece manga and anime series. It is crucial to understand that Vergo did not possess Law’s physical heart in the conventional sense. The term ‘heart’ here represents a surgically removed organ utilized as leverage.
The importance of this situation stems from the Devil Fruit ability of Trafalgar Law, the user of the Op-Op Fruit. This power allows him to create a ‘room’ where he can manipulate objects and rearrange them as if he were a surgeon operating on a patient. One crucial application of this power is the ability to remove and exchange people’s hearts, placing them into another person’s body. The individual whose heart is removed becomes paralyzed and extremely vulnerable, essentially at the mercy of whoever controls their vital organ.