Another aspect could be the world - building. The fanfic could expand on the lore of the Elder Scrolls universe where Alduin and the Dragonborn exist. It might describe new locations, ancient cultures, and the magic that surrounds them, all of which add depth to the overall story.
One interesting aspect could be the exploration of the relationship between Alduin and the Dragonborn. It might delve into their power dynamics, like how the Dragonborn's abilities are pitted against Alduin's might. This could include epic battles and the strategic thinking involved in their confrontations.
The character development of the Dragonborn outside of the main quest is also an interesting point. Without the adult content, the focus could be on how the Dragonborn grows in power, wisdom, and leadership. How they interact with other characters in the world, form alliances, and overcome challenges not directly related to the main Alduin - facing plot.