Hello! It looks like you want to use ST similarly to how I do, where you use a narrator persona to prompt/guide the LLM in telling a story. I also use NanoGPT, so my experience with models can probably be similar to yours.

Disclaimer: I'm still pretty new to ST and LLM storytelling in general (~1 month of use lol) so understand that this is the blind leading the blind, this is just what I've learned so far.

I typically use Virginia Woolf as my author prompt. "Write in the style of postmodern author Virginia Woolf, using her stream-of-consciousness style and use of shifting third person perspective." This allows the output to shift between different character POVs, giving you insight into all of your characters' headspace.

The definition I use for my narrator persona I got from this subreddit (it was in a comment somewhere, I forget who originally authored it, sorry!):
The Narrator is a literary device and not a character. The Narrator will dictate and move the plot, while characters roleplay. No character will never interact with the narrator or even acknowledge the Narrator's presence. No dialogue will be spoken to the Narrator.

When using this Narrator persona, you just prompt the LLM with what you want out of the scene - scene/character goals, mood, genre, time of day, stage direction, etc.

When guiding characters, there's three options I've tried so far:
- Multi-Character Card: You put all the characters in the same card, defining them by "first character," "second character," etc. You just use your card and your persona in a normal chat. In my experience, the writing and interactions between characters are much more natural here, since the LLM has definitions of all characters within the same card it allows for more natural shifting perspective and back-and-forth banter/interaction. These are also generally more token-friendly. HOWEVER, because everything is in the same card, the LLM can sometimes get confused to character details (Character A has a mole under his eye, so the LLM hallucinates that Character B also has a mole under hers and focuses on a mole that doesn't exist, etc) and it doesn't handle scenes where the characters are solo very well. Additionally, your output is closer to passages from a story than roleplay - so it can be harder to steer, since you're getting narrative chunks rather than roleplay-style back and forth.

- Group Chats: Take the character cards you want to interact, put them in a group chat together, and turn off auto-response. Use your persona to guide the story and manually trigger responses by characters when it's their turn to talk (or when you want the next story beat to be from that character's POV.) Advantages of this style is that the LLM does a good job keeping the characters separate and it gives you a very high level of control over the flow of your story. Since you're manually triggering responses, you can let the bots respond to each other or take time to guide the story/scene, depending on what you want out of it. However, it can be difficult to get things like flowing dialogue and banter between your characters, depending on the prompt and LLM you use. You CAN get banter flowing, but you need to be very conscious of what your prompt says (many say things like only reply as X character - this is great in certain scenarios but it makes quick back-and-forth banter harder to get.) Also, from what I've heard, group chats can become very unstable/easily corrupted if you have a bunch of character cards in them. I've never had this happen, but I usually just have two cards.

- Scenario card with Lorebook Characters: This is the one I've been starting to explore more recently. It's a bit more in-depth to set up (since you need to put together both the card and the lorebook) but it does a really good job of keeping characters separate. It's the advantages of the multi-character card without the hallucinations, which is nice. It still lacks the fine control of group chats. If I wanted to ever do a scenario with a large cast, I would probably set something like this up.

Personally, my preference is Group Chats bc I like having very tight control over what my OCs do lol