Subtxt has a rich narrative framework powered by AI to spot gaps in your story and generate content to patch them. It's got tools like Narrative Agents, Subtxt Muse, Premise Builder and Storyforms to construct narrative architecture and consistency. It's geared for novelists, screenwriters and playwrights, but has a range of pricing options for different levels of use.
Another option is Novelcrafter, a full-featured writing environment with features like a personal Wiki to record story details, multiple writing modes, and AI tools. The Codex is a central repository for characters, locations and other story elements, and it's designed to keep your story organized and consistent.
If you're looking for something more collaborative, StoryNest.ai has AI tools for character creation, world-building and story analysis. It can handle multiple formats, including interactive fiction, novels and scripts, and has tools like AI-assisted editing and proofreading. It's designed to help you craft compelling stories and to collaborate with other writers.
Last, ProWritingAid is a general-purpose writing assistant that can offer detailed story critiques, readability analysis and passive voice detection. It can be used in conjunction with tools like Microsoft Word, Google Docs and Scrivener, and offers a range of tools to help you improve your writing style and structure.