This one I really liked because of Colin's belief in Selene and how he makes himself vulnerable to her. Everyone who knew about her powers has always been afraid of her, but he isn't. He trusts that she won't use them to cause damage. Somehow he sees into the heart of her and always believes the best of her.
It's understandable that Selene's past makes her distrustful of covens and Magus Corps. I can also understand that she doesn't want to be just used or wanted for her powers. However, I did find the way that Colin dealt with her past a little dissatisfying. She had to take his word for it that the issue was dealt with. She didn't get the satisfaction of seeing justice done with her own eyes or seeing her nemesis get punished, so it was difficult for her to obtain closure.
She's afraid to accept all he offers because she's experienced too many rejections and betrayals in her life, and she fears if he does the same to her, she won't survive. However, in the end he proves to her that he can be relied on -- even though she had turned him away -- and in one of the great traditions of romance, she finally realises she can take the risk of trusting him to always have her back... and they live happily ever after. (Literally, because unprotected sex with warlock will make a witch immortal! Convenient, eh? LOL)
Oh, and I absolutely LOVED Bitsy the ferret!!!