This isn't the "what radicalized you" line of questioning. I always read those as the last straw. I'm more interested in your first steps.
I know everyone's journey is different.
Mine was realizing that despite being a complete asshole, I give a fuck about everyone.
Obama didn't close Guantanamo Bay or end the wars in Iraq and Afghanistan. His campaign had been my introduction to politics, and his first term taught me that I definitely wasn't a Democrat.
I guess I've always been left-of-center besides that. Being racist or anti-gay just didn't make any sense to me even though I was surrounded by people who were both (military community).