The development of the harem concept itself. It's not just about having multiple characters interested in Hinata. It's about how they come together, how they handle jealousy or competition among themselves, and how they all contribute to Hinata's growth as a character. In some fanfictions, they might work together to protect Hinata or the village, which further deepens their relationships.
Character relationships are key. The way Hinata interacts with the multiple characters in her harem, like Naruto and others, is important. Their mutual respect, admiration, and sometimes unspoken feelings create the basis of the story.
The Naruto universe setting plays a big part. The ninja world with its clans, jutsus, and politics provides a rich backdrop. For example, Hinata's Hyuga clan status can influence how the other characters in the harem view her, and how they interact within the framework of the clan's traditions and expectations.