Your writing pet peeves

[Arrow-Jolteon]

Karma Houdini- Any time a character does something incredibly amoral and suffers absolutely zero consequences for it. Expect people to excuse it with "but they have a tragic past!!!" as if that somehow makes every atrocity they committed a-okay. Like dude, I'm sorry that Emo McPrettyBoy had no friends as a child, but if his response to that situation was becoming a murderous terrorist, then he's crossed a line and needs to account for all the people he's killed. Especially if there are other characters in the story who have suffered far worse things and didn't become evil because of it. Please do keep in mind that "consequences" here doesn't mean "punishment"; they are not the same thing nor are they mutually exclusive. If a character spends a good chunk of the story being a murderous jerk, then it's only natural and justified that other people would distrust them and even shun them for a while. That's a consequence.

Making established characters incompetent/weak/stupid/jerks to make a new character look good in comparison- I feel this is pretty self-explanatory, but it comes with a word of advice: if it's necessary for everyone in a story to be nerfed just so your new character (be they an OC for a fanfic or just a character you introduced later in an original story of yours) can shine, then the real solution is for said new character to be rewritten so they can shine on their own merits rather than by upstaging the rest of the cast.