You would probably need to use something like Visual Novel Character Creation Suite to generate a character and a dataset for LoRA training, and then train a LoRA for each character. LoRA are adapters you plug into larger models to help it generate whatever concept you want, in this case it would be a character. With a well-trained LoRA you shouldn't have any problem with character consistency.
If you're trying to get started with generating locally, here's a tutorial for Comfy UI.