It's in his DNA - Book one in the Stormforce series

The Faerie Guardian

She's fae. He's human. He should never have followed her into the magic realm... Violet has one job: protect humans from dangerous magical creatures. It's a job she's good at-until the cute human guy whose life she just saved follows her into the fae world. Now she's broken faerie law, risking her future at the Guild...

Unbroken (Shattered Promises, #2.5)

Alex thought things were already complicated, but then Gemma shows up possessed by Stephan and she wants to kill him. Normally, he would eliminate someone in Gemma’s position to protect himself, but his feelings for Gemma won’t allow him to do that. She’s too important to him and he knows he has to save her without hu...