WIP Joy Challenge - Day Six: Which Character Is Hardest For You To Write?

For the month of January, I'll be taking part in the WIP Joy Challenge, created by Bethany A. Jennings (found via a share from Adam.C.Macdonald).

Right now, I'm struggling most with secondary characters and finding a balance between making them real, well rounded characters, without them taking over the story.

I think my problem might be I don't understand them, and what makes them tick as well as I do my main characters. Mostly, they react they way I want them to, because they're filtered through the protagonist, but sometimes they're difficult.