Since it's about Alpharius, his brothers - the other primarchs - could potentially make appearances. And within his own legion, there may be lieutenants or advisors who are key characters. Additionally, any adversaries that he faces, whether they are from alien races or other parts of the Imperium, could be main characters in the sense that they drive the plot forward through their conflicts with Alpharius.
I'm not entirely sure as I haven't read it in detail. But generally, it might be about the journey, battles, and character development of Alpharius as a primarch.
I'm not sure specifically which works are most popular in Alpharius Novel as it might not be a widely known mainstream publisher. However, it could potentially have a variety of science - fiction or fantasy novels. You could try checking on specialized book review websites or forums for more information.
You can start by searching for 'Alpharius Novel' on major online book retailers such as Amazon or Barnes & Noble. They usually have a wide selection of books from various publishers.
In this type of fanfiction, the main characters associated with the 11th Primarch can vary widely. There could be Inquisitors who are either investigating the 11th Primarch or working with him. These Inquisitors could bring their own motives and agendas. Tech - Priests might also be important characters as they could be interested in any new technology or knowledge that the 11th Primarch might possess. And of course, there could be Chaos Lords who see the 11th Primarch as a threat or an opportunity for their own dark purposes.
Magnus the Red is also an interesting choice. Given his connection to the warp and his fall from grace, there are many stories that can be told. Maybe a fanfiction where he tries to redeem himself in some way, or a story that delves deeper into his relationship with his father, the Emperor, before his downfall.
The Primarch Horus is often a very popular character. His fall from grace and the events leading up to it are a major part of the Warhammer 40k lore, and in fanfiction, there are many interpretations of his motives and actions. Another popular one could be Magnus the Red, with his powerful psychic abilities and the complex relationship he has with the Emperor and his fellow primarchs.
There could be a mage character who acts as a guide or ally to Saber. Maybe there's also an antagonist, like a dark knight or a powerful sorcerer.
Among the main characters besides Rimuru are Gobta. He is a goblin who is rather comical at times but also shows growth throughout the story. Then there is Diablo, a very powerful demon who becomes Rimuru's subordinate. His power and knowledge contribute to Rimuru's rise in the world of the novel. There are also other characters like Milim, a dragonoid with a child - like personality who has her own impact on the overall plot.
Maybe there are friends of the dad or some antagonists who oppose the dad's heroic actions. There might also be neighbors or colleagues who play important roles in the story.
There could be characters like Rick. He often has interactions with Michonne in the broader 'The Walking Dead' universe, and might also be present in the graphic novel to some extent. Another one could be Andrea, as she is also related to Michonne's story.