Happiness
They started out as mortal enemies. They weren't sure how, but they eventually fell in love with one another. There were no secrets between them. Heinz even knew about Perry's host family (although, he knew he might not be able to meet them). They could read each other like a book. If one was happy, the other was happy. If one was sad, the other would do whatever it took to make him smile.
To say they were happy together...didn't even begin to describe their relationship.
