The Holly King is associated with the darker half of the year. He has a connection to the waning of light and the approach of winter. He is often seen as a symbol of the more somber and introspective aspects of nature during this time.
One common theme could be loyalty. Given the nature of Daryl Dixon's character in the original show, loyalty to friends or comrades like Gene Dixon and within the context of Trinity might be a big part of the fan fictions.
I'm not sure. To determine if Holly is a horror novel, you'd need to look at factors such as the tone, the presence of supernatural elements, and the overall mood it creates. Without that information, it's hard to say for sure.
Daryl Dixon isn't gay in the comics. The storylines mainly revolve around his adventures and struggles in a post-apocalyptic world, not his sexual orientation.
It depends on their popularity and the creativity of fans. If people are really into their characters and potential relationship, fanfiction could definitely exist.
I don't think Dixon Hill is a real novel. It could be a name given to a fictional work in a movie, TV show, or game, but not something you'd find on the shelves of a bookstore as a genuine novel.