Sophia, our teenaged heroine, has a particularly well-developed moral compass for a such a young woman. She's in love with Derek, who has been nothing but wonderful to her, but she is fully aware of his darker vampire nature, and she is conflicted about all that he's done and still might do. She wonders if she's fallen for a monster. So do I.
This is a common theme in much of paranormal fantasy. It's hard to posit a centuries-long lifespan and not include a history of misdeeds and callous choices. Life has not always been as easy as it is in twenty-first century developed countries and the arbiter of moral choices was likely different in the Middle Ages, before running water, electricity, and IPhones. So, choices that were made when slavery was an accepted aspect of life (like, say, in Jesus' time), take on a different ethical timbre in light of the social mores and accepted practices of the era.
But what about more clearly defined moral choices? As I'm reading A Shade of Vampire on my Kindle, I'm listening (still!) to J. R. Ward's Black Dagger Brotherhood series on Audible. I'm up to Lover Avenged—Rehvenge's story. Rehvenge is a drug dealing bookie pimp--not to put too fine a point on it. He routinely engages in acts of depravity. How is Ms. Ward going to reconcile that with him getting his HEA? I won't spoil it for you, but you know he does, so it's an interesting question. One thing J. R. Ward does better than anyone, though, is to get into the heads of all her characters so we can identify with the humanity there, and relate to even the most morally challenging characters. Which is how she makes it work. Lilo Abernathy does an excellent job in this arena as well, making potentially unlikable characters—or at least characters who do unlikeable things—relatable.
Another example of this phenomenon is found in Kresley Cole's Immortals After Dark series. I had trouble with this one, because the actions of one of the villains Ms. Cole transforms into a romantic hero go over the line, even for me—and I'm inclined to forgive my fantasy characters quite a lot. As the series progresses, it turns out that one of the bad guys is the long-lost love of one of the heroines. As a result of their love, he comes to see the error of his ways, but those ways were horrific. I just couldn't go there, no matter how sorry he was or how much he loved his mate. I couldn't overcome my revulsion at what he'd done.
But that was the exception, not the rule. Most of the time, if the female protagonist can forgive the tarnished hero, so can I. Mostly because I want to believe that love heals and changes people for the better. I also want to believe that when two people are committed to making it work, it usually does.
In others, the impropriety is a bridge too far, and there is no going back. These are the waters that authors must navigate between their own convictions and attachments to the characters they create and the need to garner empathy for their creations on the part of their readers. It can be tricky. For example, a lot of readers clearly prefer female characters with little or no previous sexual experience as mates for their über alpha males (most of whom have had plenty of willing women). This is a trope that burns my butt, but I'm guessing that these tendencies reflect the majority opinion out there about the relative acceptability of multiple partners for men and women. I've written about how I feel about that here, and once again, Kresley Cole is the exception to that rule.
In the end, the question of how bad is too bad and how far is too far is in the eye of the beholder. Most of the time, most authors get it right for most readers. But there is no such thing as making everyone happy all of the time. So accomplished authors, like Lilo Abernathy, will continue to grapple with these questions while they ply their craft and shape their drafts and work to find a way to walk the line between realistic fantasy and characters who behave in a morally acceptable manner. Tough stuff, for sure.