When I initially began planning characters for my story, I only had to mains. Two morally ambiguous guys that only do things for their own selfish reasons. They enjoy drinking, stealing from thugs and fighting, and they get into trouble all the time. Before I even started writing, I realized these two guys would need someone sensible to hold their leash, or nothing would get done. Enter MC #3, the annoying girl. I actually like her. She's sweet and innocent, and does things out of the goodness of her heart. She's the one that has to keep reminding these guys that they actually have something important that needs to be done. But that she's such a goody-two-shoes makes her kind of annoying. What is my question? Good question. Not sure. How do I make characters that needs to be annoying less annoying to readers? When is a character too annoying? Am I the only one who kind of dislike those good characters? I don't mean she's perfect, she's not, but she's just really kind (to a fault actually) and while I like her for it, it makes her annoying as well... so saying that I don't like good characters make no sense. I guess I'm worried I like her just because she's my “baby” and I couldn't possible dislike her for any reason. I'll stop here. While I'm still making some sense.
Stop making them as caricatures and make them human beings. It sounds like you are writing only one aspect of their personalities. If you are annoyed by the 'goodie-twoshoes-ness' of the character, you are probably not making them up of the complexities that make real humans. Example of an observation of a friend. I know a girl. I very nice girl and someone that anyone would call a good girl and goodie-goodie. Good student, sweet and all that. She didn't swear and always polite. However, she smoked and though she would not swear under any circumstances for a morality reason, she had no problem moving in and living 'in sin' with someone. Remember that even the 'wholesome' people have traits that are atypical to their niceness.
She is not (at least I hope not) a bad character in that manner. She is practically a child trapped in a woman's body due to being overprotected her whole life, and never had to do anything by herself. Because she has hardly ever been exposed to the outside world, she is naive and when reprimanding these bad guys she is, like a child, just repeating what she has been told by her parents. “Adult” things like sexuality and violence, even just in movies, scare her. So while I really like her, she can be annoying sometimes because of this. Because of how she can be such brat. But she is a brat because she doesn't understand how to act adult.
Does she have to be liked? And if you explore this background of hers in the story, people will start to understand her, which will make her interesting. Interesting doesn't equal "not annoying" but it does make them tolerable. Characters don't always have to be liked. Brilliant example of such a book is Perfume by Patrick Suskind - all the way through, you are told that the MC is sub-human, evil, a monster, murderer, repulsive etc, and trust me, he was one of the most intriguing characters I've ever read about. The reader is led to both be absolutely fascinated by the MC as well as repulsed by him, leading the reader to want to know his story all the more. Think the film Black Swan as well - you need to watch that if you're writing about someone trapped in a woman's body. Nina is exactly that - a woman who cannot grow up for various reasons. Very well done. Or perhaps the opposite where there's a woman trapped in a child's body in Interview With A Vampire
Hello. I suggest watching the anime Samurai Champloo as they have the same set up for three main characters and they pull it off extremely well.
Seems to me her flaws are naiveity (I can't spell today...), cowardice and perhaps incompetence. As she grows and meets tougher situations, she can grow into a more mature and capable person. Have you seen the movie "Spirited Away"? It provides a really great example of that type of character growth. I've also met goody-two-shoes types who are just self-righteous, judgmental, gossipy, prissy etc.....but your description makes me think the former scenario is the case.
This set up is very similar to an anime called samurai champloo, you should check it out. In that the girl uses there selfishness against them.
A character can be an annoying person, as long as she's also entertaining, interesting, thoought-provoking, etc. She can annoy other characters without annoying the reader. In fact we like to see one character create drama and tension by irritating another. Just make sure she's three dimensional and not boring. Or annoying for me to read about.
She sounds like Tohru Honda from Fruits Basket, if you've seen that anime. You don't want to make her a goodie goodie because she will be written off as a Mary Sue. She should not be naive, innocent, charming, and vulnerable. All of those traits combined will make her unrealistic. Real people have problems and faults. She can be nice, but nice does not equal naive. Try making her more wild, or quirky. If she is kind of weird it might flesh her out a bit. Or you can make her sort of a rough babysitter figure to the guys. For example, she can be short tempered and angry when the guys screw up.
If you can find a way for her to be somewhat entertaining, then I think it is fine. You aren't supposed to like every single character, some characters are supposed to bug you. But as long as you keep them relevant and entertaining, they are still interesting characters. Maybe you can make it a thing for the two guys to try to do their stupid antics without getting caught by the girl, or something.
Let her grow through the story and not remain static. I think not letting characters grow is one of the biggest mistakes people can make. One of my current main characters killed a man in revenge but he's grown beyond his past and is remorseful even to the point of his guilt driving him to do things he wouldn't ordinarily do. I know he'll move past this as well. I would just go with it and see where she goes. That's what I did with my most recent group of characters. So far so good. One did start off feeling a bit annoying to me because she's a bit of a pacifist and doormat. She's grown beyond it a bit and as I write more about her it makes more sense why she behaves how she does. Odd as that sounds. lol I think sometimes we write characters that are so unlike us it can be annoying. I'm very no nonsense. If someone offends me I will tell them they did. I didn't use to be. I suppose that's why I find her annoying at times. She's more like my old self than my current self and I didn't much care for my past self.