That's always the case with secondary characters, or anyone that doesn't have to do a lot heavy lifting. They get to move through the background, only surfacing to do their thing, which tends to be demonstrative and interesting. Meanwhile the POV characters have to hold the reader's hand, especially through the boring or more subtle parts... totally different strategies as far as building a cogent narrative are concerned.
Oh that's nothing to be worried about. Secondary characters tend to be easier to grok than primary ones. You know what role you want her sister to play and even if you don't know every line of dialog you don't really need to. She's big and brash and you can crash her into a scene and have her do that no problems. Secondary characters can be (and often are) archetypes, but MCs have much more nuance to them and you need to know the finer points of them. If her sister broke up with her boyfriend that's not something that you need to think about for the rest of the book, that's one scene, or no scenes. for Mercedes that might be something that sparks a book long journey of development, making her weave between introverted and more confident depending on setting.
I've been thinking about Mercedes and I think I'm going to give her a personality lift. To be honest the picked on, self-conscious teen thing has been done to death and beyond. I know they say cliches aren't so bad if you do your own thing, but it's been overkilled too many times in my opinion. That's why I was thinking about a different approach. With this one, Mercedes wouldn't care about being chubby, has a very happy, upbeat personality, and is also a bit dingy. The Alpha Bitch in school even gets pissed off because her picking on Mercedes doesn't phase her. Although with this I'm not sure about doing dingy, or full on space caditz. The ditz would be funny yes, but I'm not sure it'd be easy to reign in believably when the story got serious. Mercedes isn't an idiot by any means, she'd just kinda be off in her own little world most of the time.
I quite like this development. I like the idea of making her generally happy and upbeat but a bit dreamy and always living off in her own head. You can do lots of stuff with that, depending on the direction you want to go with it. She could be dreaming about being a superhero, and then discovers what it's really like to be one. Or she could be dreaming about boys, or the job she wants in the future, or dreaming of Christmas with her family. All these things that let you kinda set her up as being someone who is maybe a bit introverted but also who's happy in her own skin. She's thinking one way or another about where her future will take her, and then she suddenly has her 'future' (in a sense, because she'll always be a super hero) just shows up and it's not what she dreamed of and now she's trying to deal with who she is and trying to balance that with what she wants. Yeah, there's lots to work with there.
The only way to make someone struggle with their mediocrity is by showing their lack of successes, not by their character traits. She doesn't get the guy of her dreams. She doesn't land the awesome job. She can't complete that difficult task. If you take a person with mediocre traits and make them achieve great things, without some heavy cost, then we can take this discussion to a Mary Sue thread.
Sorry, I can't agree with that. And I don't agree that 'mediocre' means 'failure' either. The average person doesn't get everything they want, but they get some things they want. And they consider themselves lucky to have a good job, or to have a loving partner, or to have the one big success that they have managed. And while it might take them a while to achieve absolutely everything they want, they typically are going to at least get to 'acceptable' in most aspects of their life reasonably quickly. They don't make as much money as they might like but they aren't desperately poor either; they might want a different job but they are ok doing what they do right now. As for a mediocre person achieving great things; the struggle with that is in their head. Depending on the exact character there's two different ways to look at this; firstly if the character under estimates their abilities and doesn't believe they can achieve more than they already have. This kind of character being thrust into doing exceptional things will be overwhelmed and terrified; they will be scared to use their powers because they believe they'll fuck up and they'll hurt people and nothing good can come from them over reaching their limited ability. And, through the course of the story, they would typically learn that they are much more capable than they imagined. They will be forced into a situation where they have to push and have to see what they are made of, and discover that they are more of a hero than they ever thought. And then there's another type of character; who will never believe that they have succeeded no matter how far they have gone. To a certain kind of person (and I am one of them) it really doesn't matter what anyone else thinks of their achievements. What matters is what they think of their achievements; and they will feel like a failure if they haven't gone as far as they think they should have. And having people show up and say "Oh but you're doing better than me, what do you have to be upset about?" makes them want to feed people their tonsils. Because even if they are making lots of money, even if they have a good partner, even if they have a nice secure, stable life; if that's not the life they wanted then it doesn't mean anything to them. It's less than they believe they could achieve, it's less than they feel they should achieve. And thus it will always be a failure. And that's where the conflict lies with this kind of character. Because they may well achieve great things, but there's a good chance they won't acknowledge they did anything at all. To put it in a super hero context; it won't matter to them that they saved 99 people, they let the other 1 person die and they feel responsible for that. After all; they have frikkin super powers, how the hell did they let this happen? They were supposed to save everyone. And they'll hate people who try to celebrate something that they consider a failure. And slowly they will have to learn that they can't ever hope to save everyone; that it's not their failing that bad things happened to other people. And that's very very hard for them to learn. It's still something I struggle with; it feels to me like I should be able to do something. It's very hard for this kind of person to just accept that they are powerless, doubly so when they are super powered because they can do so much. They just can't do the stuff they really care about. They will feel that it's their fault that super villains decimated the city; because they are Superman and they can do anything, so how the hell did they let this happen? There's lots of ways that people can be mediocre and still be struggling. They don't have to be a literal failure to have real problems. Either because they believe they could be more, or the believe they should be less; either way. The struggle is against their own inner demons, not against the actual world around them. The external conflicts are kinda, well, meaningless. If you don't get the guy of your dreams what do you do? Well, you look for someone else, right? You don't get the job you want then you keep on looking. Because no matter how much you set your heart on one thing there is plenty more fish in the sea. You overcome these by just continuing to try. And even the mediocre find something that fits them eventually, and it doesn't cost them anything really. They just persevere. But when the conflict is inside them, when they are struggling with their self image and how they perceive themselves; how they contextualize their efforts; then that's something where it really doesn't matter what stuff happened. What matters if how they feel about it. A story is a journey, an arc, a path of personal development. To say that a character who is very 'normal' at the beginning and they end up achieving great things is a Mary Sue is almost a non-sequitur because that's every character. The hero has to go and seek out the ability to overcome the bad guy. Sometimes that means finding the magic weapon, but often that means growing as a person, conquering their doubts and fears and becoming personally strong enough that they can face down this great demon and overcome them. There's two parts to achieving great things. One is the means, in this case super powers. The other is becoming the kind of person who can use those means to do the right thing. It doesn't matter who they were when they started; they build more inner strength and they see it through. Starting your journey as 'normal' isn't even close to being a Mary Sue; even if you end up saving the universe. Doubly so if the story actually looks inside their head and explores why saving the universe is something that they have to really struggle with.
