The reader begins to appreciate the man behind the harsh mask. The reader also learns about Isabel. She is a strong willed woman, willing to sacrifice her future for the sake of her sisters. Both characters possess admirable qualities, including honor, loyalty, honesty, and compassion. For chemistry to work, a reader must care about what happens to these people.
Conflict is an important factor in creating chemistry in a romance.
Basically conflict is created by obstacles that stand between these two people finding happiness with one another. The conflict can be internal, meaning something in a character's thoughts or value system has erected a defense against the other person, external, or both. In Devil's Honor, the conflict is mainly internal. Justin at first doesn't feel he is worthy of Isabel. Isabel thinks he wants too little from a relationship.