Reasons Why You or Your Readers Hate Your OC:
Have you ever created a character and, somewhere down the line, you learn your readers began to hate them for all the wrong reasons? Maybe you already hate them. You don't know why or where this hatred comes from, but you're unwilling to throw this character away for whatever reason. These aren't characters that you wanted to portray as evil or villains, but somehow you can't stand writing them!
1. Too Many Bad Decisions + Forgiven Easily
Some characters make mistakes, while others make so many mistakes that it almost seems intentional. This inhibits the story's progression, wastes the time of both you and the audience, and, on top of that, a character fails to learn from their mistakes and thus repeats them. Characters like this must face consequences for their actions; let them be affected directly, rather than having others and the environment bear the brunt, and don't let them be forgiven easily for it either.
Equally as bad as a character with too many mistakes is a flawless character. The whole world bends for them, and they have no issues to resolve. You probably already read and saw these types of characters, but make sure the flaws you've given this character aren't minuscule, like always forgetting to put the milk back into the fridge. It must be a flaw of belief that's deeply ingrained in the person; external problems don't make an interesting story.
3. Overshadowing Other Major Characters
You dislike this character because they've taken the spotlight. When readers fall in love with a character, they are willing to cheer them on and expect to see them succeed in reaching their goal. Don't let somebody else steal that away from them! That's what a villain does, and you are not trying to write that. A character that you hate can also steal from the villain. So make sure your villains are not being overshadowed, too. Instead, redirect the character's goals elsewhere or make them a supporting character who helps others pursue their goals. If you can't do that, never make it easy for them to take something away when they don't deserve it.
Similar to stealing the spotlight, don't let this character get away without trying and failing. You cannot naturally be smarter, stronger, and faster than another character already established as a smart character. If they are, then show the audience that this character worked twice as hard to gain their position and deserves it too; otherwise, they've appeared out of nowhere and ruined the story for everyone.
You might hate this character because they've replaced somebody else. Did you kill a character or multiple characters and introduce this character solely to fill that void? You can't replace a beloved character who has either died or left the main group or the story in general; it's like cheating.
They are a new character, and you only hate them because of that. The effect only happens when you've had an established group of characters and attempt to shove this new character down the audience's throats. Be slow and steady when introducing them; they shouldn't come bursting in. Let them make a few appearances and be helpful once or twice before increasing the frequency of their interactions with others around them. This way, readers and you become comfortable, and the harmony between existing characters is not destroyed, only slowly changed to make room for one more.
They've done nothing, and they can't do anything about it. We typically reserve this role for background characters who have no significant impact on the plot. Perhaps they cry or complain too much instead of growing, and thus are useless in that aspect. The only way this would make sense is if they are a temporary character; we can't keep these types of characters around for too long, or it'll drive readers up the wall. What's worse is if you've built this character to have a strong purpose and more important roles, but you keep writing them in a way that inconveniences others. I strongly recommend assigning these important roles to another character who is better suited to manage them if you, as an author, can't change the personality or help the character grow out of their shell.
This is more aimed at artists with characters they can't stand. If you hate the character, it's likely because of how they look or how you imagine them in your head. You've accidentally given them an evil glare, or the colour of their shirt is too bright, or maybe they're unattractive to you. It's not the character's fault; they might need a makeover.
This is a significant issue in certain media; the characters themselves did nothing wrong; they just happened to be in the wrong place at the wrong time. Please remove them from the area if this character is constantly positioning themselves between two or more characters that are supposed to be written as romantic partners. They don't need to be there all the time; give this character a hobby or other friends. It's awkward to have a third wheel or an unintentional jealousy arc. It also frustrates readers when all this character's role is to be a love interest and nothing else.
It's best just to admit that somewhere within you, even if you're a woman, you can't write women, or you have some form of misogyny. There are many women in the media who are great and strong, but they often become victims of poor writing. Find a good representation of a woman and read all about her, and then come back when you are ready to resolve your inner misogyny. This may take years to master.
Sometimes, all it takes is one BIG mistake, and instantly, everybody hates them. To avoid criticism, ensure the audience has a deep understanding of why a character might do it. Let them make mistakes that fester and confuse them because of their ideology/belief, and convince readers that what they're doing has reason, motivation, meaning, and unforeseen consequences. If the idea this character has is obviously going to lead to a massive problem, don't let readers predict it; instead, catch everyone off guard when they discover it was an unintended outcome. Put yourself in their shoes, look through their perspective. If this is a mistake that needs to happen, check if any other available characters could make that same mistake and not be hated.
12. Unintentionally Mean-Spirited
You may need to adjust the way this character speaks; they must appear clueless about the situation around them, or they speak out of turn too often. They also shouldn't step out of their role to overpower the conversations of other characters. Please review all their interactions and adjust their tone of voice. See if that changes your feelings for this character.
13. Reflection & Projection
So you've accidentally made your high school bully or mom into a character, now you want to punish them. You have to ask yourself what's more important, the story or your irrational vengeance? You can't force the readers to love this character if you keep seeing the parts of yourself you hate in them. Resolve the problems you're facing and split your story from the real world.
This one might be obvious, but both you and your characters shouldn't be racist. You create characters you know people will love, but these same characters are racist toward your POC. This is a risky move if your story doesn't acknowledge that this is wrong and represents a behaviour that needs to be corrected. Please don't end your story or skim over it without addressing the issue or making it a major conflict. Racism is a persistent issue that affects real people. The audience will absorb what you write and imitate it to others. If the POC is a villain, don't let their skin colour be the root of all evil. You need to examine yourself for any hidden biases or stigmas against certain groups, whether real or fictional, and if it's something you can't overcome, refrain from writing about it. This applies not only to race, but also to gender, religion, and class.
You've bored the audience to death. When this character comes on screen, people skip, ignore, or stop reading the story entirely because of them. This is usually because the character has nothing of interest going on, nobody knows who they are, they're not connected to the plot, and they're likely isolated from the other characters; their ambitions seem unrelated. It's the type of episode or chapter you skip because it's wasting your time and doesn't play an important role. If you want them to be mysterious, give us hints and crumbs of their position in the story, make us hungry for more and curious enough, but never able to connect the dots until you want us to.
If you've worn out all possible roads, then you've made an evil and hated character. Even if you didn't mean to, it's okay to accept that, perhaps they work even better as a villain. Lean into that, let them be evil, and have fun.
Ultimately, you can't stop others from hating a character you've created; it's an inevitable consequence. These are just some major and outstanding points to regulate yourself and ensure that no character is being treated unfairly.