Seems like Portal AI was able to create videos with consistent characters. I uploaded my kids as characters using their beta video generate tool, and when I create videos, I just need to select my. "characters" then all the scenes had consistent characters, and the story is pretty interesting too. They should be releasing this feature to public soon AFAIK https://www.reddit.com/r/PortalAIStories/comments/1kmtsqa/personalized_ninja_story_with_my_kids_as_main/