I have two saves currently and they are both SimLit stories. The big one is Under The Tartosan Sun and that one has 6 main characters and at least 15-20 secondary characters that pop in and out. The ladies in my profile picture, Londyn and Danielle are the stars of the show so to speak. They are my own creations. The other four are Summer and Liberty who have received makeovers and their fiancés who are my own creations. The secondary characters only include one or two premades the rest are my own. The other story Schemes & Dreams is just getting started so the cast is still growing. It's has more premades, mostly the celebrities, Judith, Brytani, Octavia, and Thorne. I gave Johnny Zest a radical makeover into a drag queen named Lady Mimi, who has turned into everybody's favorite character. The rest are almost entirely my own creations. Both stories still have quite a few of the premades still in them, but they're just background filler. Occasionally one will have a brief appearance but nothing more.
When I started both stories I intended for the sims to do their own thing and I would build storylines and dialogue from anything interesting they did that I thought I could work with. Both stories have turned into more of a situation where I come up with the storyline and then I direct the action to get the shots I want. That happened for a few different reasons, but the main reason was a lot of the main characters had careers that are part of the story but they're the type of careers that if I don't direct them to write a novel or accept an acting gig, nothing will ever happen. As I've gone on I've realized I can do something similar with the ones with rabbit hole careers. I build lots to look like and perform like their workplace. When the storyline calls for them to do something at work I send them to the lot I made and I act out their work scenes. Since they are technically unemployed I cheat them some money every sim week or two to simulate a paycheck. So they have their days free to do whatever they want when I'm off with one of the other households until I need them to 'work'. It's so much more fun to act out what I think is happening at work instead of them just disappearing for a few hours.