In fanfiction, Snape might be begging Harry to marry him because he has a newfound respect for Harry's strength and heroism. Snape, who has always been a complex character, could have had a revelation about Harry's true nature. He may also be seeking redemption through this extreme act. By tying himself to Harry in marriage, he could be trying to rewrite the wrongs of the past. It could also be a result of some sort of magical bond or curse that forces him to have these feelings. Or perhaps he's just lost his mind in a really wild fanfiction plot twist.
Well, in fanfiction, there could be multiple reasons. Snape could be begging Harry to marry him due to a complex web of emotions. He might have realized that his previous animosity towards Harry was misdirected. Maybe he's seen Harry grow into a remarkable person and feels a deep connection. It could also be a form of self - sacrifice. Snape might think that by marrying Harry, he can protect him in a way he couldn't before. Additionally, it could be a part of a larger plot where the author is exploring alternative universes or relationship dynamics that are far removed from the original story. This kind of fanfiction often delves deep into the 'what - ifs' of the Harry Potter universe.