The characters are highly complex and they exist in a world that values strength over compassion, only the strong survive. The life inside the pack mimics that of a real wolf pack with a strict hierarchy that is established through fighting and power. It is also comparable to a medieval court, the king holds his divine right to rule and the queen exists solely to please and support the king. Throw in scheming courtiers with the ability to change into wolves with sharp claws and fangs and you have the pack construct.
As the characters are basically wolves housed in a human skin and the story is laced with animalistic references and traits displayed by all. We first meet the main characters Meela and Grey it is on a bloody battlefield where they recognize each other as their soul mate, and Grey takes Meela as tribute for his pack's help in her brother's fight. From this point on Meela belongs to Grey, and in this world, a highly spirited female with a propensity for impulsive actions matched to a dog stubborn, self-assured, dominant male is going to cause problems.
We follow Meela in her journey to become the pack's Luna, a pack who are even more wolf than the one she comes from, and with a mate who has set the highest standards for her to reach as his Luna(female Alpha) and will accept nothing less than perfection. In the midst of all this and the struggle they face to form a personal and public relationship, there is one incident that will change them both and the fate of the pack completely. From that point on both Meela and Grey are inevitably changed and for them to be together, either one or both needs to change, but when you live in a world where you are taught that weakness is easily exploited and to admit defeat can potentially lead to your destruction.
Thank you @chortle for the great summary