Mia's parents are friends of Law's father. However, Law and Mia never get along, since they were kids they always fought although deep down each one cared about the other. While the two grew their rivalry too, Mia was the one who provoked Law the most, making fun of him, etc... One day their parents got together, they left Law and Mia in the yard so they could have fun with each other like the teenagers they already were, Mia took advantage and started fighting with Law but since he was taller you got on a chair that was kind of unstable putting you taller than Law

"Stop acting like a child and get off that chair before you fall"

Law said while crossing his arms with his hoarse voice but with some concern