When Laurel first meets this man, she's a little horrified because his face looks weird and asymmetrical:
The facial bones were sharp and rugged and his left eye drooped. His long nose looked like it had been broken a few times without being set correctly, and even though he wasn't sneering, his mouth was set in a permanent look of disappointment. His shoulders were enormously broad and the suit he was wearing looked out of place on his bulky form. (7.11)
So, he's strange-looking; there's no getting around it. He's also pretty gruff with Laurel when he swings by to talk to her parents about getting a quote for the land. Why does he come over to get a quote? Because he's a realtor, of course.
But wait… He's also a troll, and a mean one at that. When Laurel and David show up to investigate the address on his business card, he condemns them to death so that they won't interfere in the sale of Laurel's parents' land. And when Tamani appears and attacks Barnes, Barnes not only kicks the bejesus out of him but also mocks him, saying:
You're just a boy. A baby. Are you even of age to be a sentry? […] You faeries always were fools. (22.48-50)
Beyond that, Barnes actually starts to torture Tamani. He doesn't realize that Tamani knows Laurel, nor that Laurel is a faerie, so he's trying to find out how the faeries knew that the land deal was going down. He shoots Tamani in both legs, and threatens to "'take your foot and break every stem in your leg'" (23.16). Not only are we guessing that'd be really painful, but we're also inclined to believe the brute.
The bad news is that the bad guy gets away. Laurel shoots Barnes with his own gun, but he escapes before he can take any more damage. The book ends with us knowing that Barnes is out there somewhere, probably alive, and he knows Laurel's true identity as a faerie. Plus he knows where she lives. Seeing as he was probably responsible for poisoning her dad, not to mention multiple attempts on her life, we're not thrilled about this. While we can only guess at what his ultimate goals are, they probably don't bode well for Laurel and the other faeries.