It's likely about the adventures of witch hunters in a fictional world. Usually, it might involve their quests to find and deal with witches, perhaps exploring different regions, facing magical challenges, and having interactions with various characters, both good and bad.
Typical main themes could be good versus evil, as the witch hunters fight against the 'evil' witches. Another might be the struggle for power, with different factions vying for control over the witch - hunting operations.
Sure, there could be an old and wise witch hunter who serves as a mentor to the younger ones. And there might be a witch who is not entirely evil but is being hunted, which makes for an interesting character dynamic.
It might be about a system related to witch hunting. Usually, in such novels, there could be characters who are witch hunters, and they might have to face various challenges like dealing with powerful witches, uncovering dark magic secrets, and perhaps there are also political or social aspects within the story related to the existence of witches and the need for hunting them.
The relationship could also be developed through a misunderstanding. At first, the hunter might think the witch is a threat to all survivors. But when he sees her sparing some survivors or leading zombies away from a group, he starts to question his assumptions. This could lead to him approaching her more carefully, and eventually they start to communicate in their own way, perhaps through gestures or simple sounds. As they communicate more, their relationship changes from one of enmity to something more ambiguous and potentially positive.
The primary character is, of course, the last witch hunter. However, we can assume there are other characters as well. There could be a young apprentice - type character who looks up to the hunter and wants to learn from him. This character could add a sense of new - blood and naivete to the story. There might also be a villainous witch who is the main antagonist, leading the forces of dark magic against the hunter. And then there could be some ordinary people in the story who are affected by the conflict between the hunter and the witches, showing the impact of this battle on the world at large.
I don't know for sure as I haven't read it. But typically, there would be the witch hunters themselves as main characters. They could be strong, skilled individuals with unique personalities.