At the start of this book, I was convinced that these two were not going to work out. They hate each other so much that they are both plotting ways to kill the other and make it look like an accident. That said, lit does work out for the two of them, although they have several close calls. I ended up loving the two of them together. They hated each other so much at the start of the book that they were either going to kill each other or it was going to go the other way with them having hate sex.
They end up having to spend two weeks together on a mission, since Dragos was going to kill them otherwise. They quickly go from wanting to kill each other (and trying to) to flirting. They have very strange ways of flirting, but it works for them.
By the end of the book, the two are clearly perfect for each other, but I'm still not sure how Harrison managed that!