>>74720611I'd have the winner set from the get-go. A "new girl" should serve as an obstacle between the MC and the heroine as well as being a catalyst for growth for the heroine by being the antithesis of her. If the main heroine is a troublesome woman, have the rival be well-adjusted. They should be equal, but opposite.
I'd never write a full-blown harem because I've seen those buckle under their own weight and eventually collapse into parody. After all, they keep adding new girls to keep the series going. Not to mention most MCs are bland to the point of being noncharacters. A love triangle I would consider but you would have to write them to be a serious enough contender that the reader doubts the MC and the Heroine's bond, but not seriously enough that the meta of the story actually allows the "what if". It's a fine line.
That said, I still want that fic where two Stacies get catty with each other as they fight over you
