My choice went to Mayson. I liked her. I know this is gonna get me a lot of raised eyebrows
but I often thought that she's portrayed too much as a villain. She wasn't truly a villain imho. She was falling hard for a man who was head over heels in love with someone else, and yet who showed no clear sign of pushing her away when she tried to seize her luck. Like every other FoLC, I was very irritated with her when I first watched the show, but she sort of grew on me, to the point where I'm working on something where she wouldn't be a complete villain (I hope I can make you like her anyway, once I finish that story).
Anyway, I was surprised not to see Lex, since when I first read the question, he was the one character that immediately jumped to mind (mostly because John Shea's performance as an actor was astounding), but after all he's not a minor character at all.
Kaethel