There's also a possibility that it could be a minor Death Eater that we don't know much about from the original series. The author of the fanfiction could create a new character who was a Death Eater but is now having doubts. Hermione could be the one to find this person and start their journey of change. This would give the author a lot of creative freedom to develop the character's backstory and their relationship with Hermione.
I think it is. The plot has depth, the action scenes are exciting, and it has a good mix of humor and drama. However, it might not be for everyone depending on personal preferences.
The Soul Eater manga did end. It wrapped up its plotlines and gave a satisfying conclusion to the fans. However, opinions on the ending may vary among readers.