Novela negra basically means a type of novel that focuses on crime and mystery. These novels usually have a lot of twists and turns to keep readers engaged and guessing until the end.
Some of the best fanfics often have detailed character development and an engaging plot. Look for ones that really dig into the personalities of Count D Leon and Uke Leon. For example, a fanfic that shows how their relationship evolves over time, through different challenges and events. Maybe there's a fanfic where they have to team up against a common enemy and in the process, their bond deepens.
You can try looking on popular fanfic platforms like Archive of Our Own (AO3). There are often various fanfics related to different characters and pairings. Just search for 'Count D Leon' and 'Uke Leon' in the search bar, and it should show you relevant stories if any are available.
Hunnigan could be a great addition. She could provide Leon with information and support from the outside, and her presence could add some tension as she might be suspicious of Ada's motives. Another good character is Wesker. His past connection to Ada could create more drama and conflict in the story. He could be a shadowy figure trying to manipulate the situation between Leon and Ada.
" 13 Minke Street " was a popular urban novel by a pure little dragon. The novel was published on Qidian Chinese website and was loved by readers. The story tells the story of Cullen traveling to a strange world and gaining the ability to resurrect the dead. This book could be read or listened to on the Qidian Reading App. The recommended audio book streamer was Beiming Yousheng. They had carefully adapted it, and the voices of the characters were rich, giving the readers a strong sense of immersion. Now, you can even get an experience member by going to Qidian to listen to books. You can read authentic books and listen to authentic audio on the Qidian Reading App. The male lead was Cullen Immoles. He was calm and rational, outspoken, thoughtful, and had a clear distinction between good and evil. The female lead was Eunice Allen. She was smart, gentle, cute, considerate, and sensible.
The Resident Evil novel with Leon as the main character was Resident Evil: East of Eden. The other search results did not mention any novels with Leon as the main character. Therefore, I don't know of any other novels that have Leon as the main character.