Witch Hunter by Emma Dean

What happens when a witch hunter stumbles upon the prince of the demon syndicate? You get an angsty enemies to lovers romance where the guy really hopes the girl doesn’t find out who he is, and the girl hopes he doesn’t notice that she’s stalking him…

Nova is a convergence – someone who displays traits from two separate bloodlines.
She’s a hunter as well as a witch who just received her first mission from the Council of Paranormals: investigate the reports of out of control magic in Seattle, an unclaimed territory.
What she doesn’t expect is the intense connection with a mysterious paranormal when she first arrives. She has no idea what he is or who he is. She tries to stay away from him, knowing there’s a good chance she might have to arrest or kill him, but she just can’t stay away.
Dex is a Nephilim – stronger than angels or demons, and hated by both. His adoptive father’s syndicate laid claim to Seattle and has held it for the last twenty years.
Every day is the same – making sure the territory is secure, protecting those within their borders, exacting justice and punishment when the rules are broken. Dex lives only for the violence and bloodlust. Until her. Nova makes him feel alive for the first time in his life, but can she survive what he is?