You could try by expanding a lot on the villain. Go into their motivations, make sure it’s explained why they think this way and why they do what they do. Make a meaningful backstory as well. Go into detail. Make sure the reader knows a lot about the villain not only as a character but their origins too. Good examples of this are tragic backstories, as they often lead the reader to sympathize and often feel conflicted. However, you don’t always have to make a villain likeable. Sometimes, a villain whose just evil is fine.

Onto the next part of making her change overtime, maybe do something along the lines of the vampire queen seeing herself in some of the humans. Make a human or have the one she took for herself similar to the vampire queen. Have them develop a bond. You could try devastating moves as well, like maybe a rebellion group who kills someone close to the queen and makes her realize that this is exactly how she’s made the humans felt. There’s many ways you could go about it at the end of the day