ORV is classified as a manhwa. It has managed to create a devoted fan base due to its combination of exciting narrative and visually appealing graphics.
To write a good Uriel character, first understand her basic traits from the Darksiders source material. She is a strong and fearless warrior. So, in fanfiction, keep her combat skills and determination at the forefront. For example, when facing an enemy, she should be decisive and act quickly.
ORV is a novel. It has a rich and elaborate narrative that is characteristic of the novel genre. There might be plans or fan-made webtoon versions, but the original and official form is a novel.
One possible fanfiction could be about War and Uriel teaming up to face a new, unknown threat in the Darksiders universe. Maybe a powerful demon that has emerged from a previously sealed realm, and they have to combine their unique abilities to defeat it.
The length of the ORV novel is substantial. It encompasses a rich and detailed story that unfolds over many pages. Different editions or translations might have slight variations in page count, but it's a substantial literary work.
One common theme is probably heroism. Given the 'War' aspect, the characters, including Uriel, might be depicted as heroic figures facing great challenges. For example, they could be saving a world or a group of people from destruction.