When writing an 'Edward Cullen Yes Daddy' fanfiction, think about the relationships. If it's about Edward and Bella, you could rewrite their relationship in a way that Edward is more of a paternal figure. For example, he could be teaching her about the history of vampires in a very nurturing way. You also need to pay attention to the pacing of the story. Slow down for important moments and speed up during action scenes. And always keep in mind the 'yes daddy' concept should be integrated in a way that feels natural within the Twilight world you're creating.