The character of Kassandra herself can make a novel interesting. If she is depicted as a strong - willed seer, her struggle with her prophetic visions and how she is treated by those around her can be captivating.
It's a bit complex to define Kassandra as simply anti or pro religion. The novel presents her with various situations that shape her nuanced views on the matter. Sometimes she questions religious practices, but at other times, she may find solace or guidance in them.
One well - known Kassandra novel could be 'The Cassandra Complex' which delves into themes of prophecy and self - discovery. It's a thought - provoking read that takes the character of Kassandra and weaves a complex narrative around her abilities.
Perhaps she gets hurt while trying to protect someone she cares about. She could be shielding a friend from an attacker's blow, and in the process, take the brunt of the injury herself. This would then set up a story of her recovery and the revenge she might seek on the one who caused the harm.
One idea could be that Naruto somehow gets transported to the world of Assassin's Creed Odyssey. He meets Kassandra and at first they are wary of each other. But as they face common enemies, like the cultists in the game, they start to team up. Naruto could use his jutsu while Kassandra uses her combat skills. Eventually, they learn from each other and a deep friendship forms.
You can start by looking on fanfiction websites like Archive of Our Own. It has a large collection of fanfics, and you're likely to find many ac kassandra fanfic there.
One common theme is adventure. Given the nature of the game world they exist in, many fanfics will have them going on quests together. Another theme is friendship, which can gradually develop into something more romantic as the story progresses.
The First Blade story and Kassandra's connection is quite complex. It involves various plot elements and character interactions that shape the overall narrative.