I acquired through reading an interest in justice and the role law could play. One book I read in my late teens was influential. In the Spirit of Crazy Horse by American journalist and author Peter Matthiessen. Written in 1983 about an individual who was part of the American Indian Movement called Leonard Peltier. He happens to still be in jail 45 years later, in what this book would tell you was a major miscarriage of justice. It profoundly affected me. The idea that law could be a force for good attracted me to the legal system.
I was predisposed to arguing. I found it interesting to pursue the right answer through discussing it with people. Constructive arguing rather than arguing in a teenager-y sort of way. I made the connection that actually the two things played into each other. I was possibly a little bit idealistic.