So as not to take over the Randomness thread. In two parts cuz of the character limit; this is part one. XD In no particular order, here are my main fanfic annoyances.
1. Mary Sues.
Now, I understand that a lot of people want their character to be the best at everything, but that just doesn't hold water in fanfic or RP for that matter. A Mary Sue
will warp the whole story, and destroy the canon just so that she can be the best, get the boy she likes and defeat the enemies.
Not all original characters are Mary Sues, and not all Mary Sues are original characters. It's just as bad if you take a canon character and then grotesquely edit them so that they bear no relation whatsoever to their former selves. A character should also not be thin; if you give no details about them, just a name, age and power description, it makes them a cardboard cutout rather than a person.
2. Allergy to "said".
It's normal to want to be creative when describing conversation, but "said" isn't really as bad a word as a lot of fanfic authors seem to think. It's OK to occasionally drop in another word, but honestly, people won't hate you if you use "said" a lot of the time. However, if every other word is a creative alternative to said, it makes the fic unreadable. Sometimes, all a character is doing IS saying something, rather than growling, hissing, screaming, yelling or muttering. Do not be afraid of "said".
3. Pairings gone wrong.
Look, if you want to put two characters together, then please pay attention to detail. Would they even like each other? Would the personality of one allow them to mesh with the other? And, most importantly, can you keep the two characters as canon intended, without having to horribly edit them? If you answer no to any of these questions, then the pairing is not going to work. That doesn't mean at all that you can't put in a pairing not hinted in the canon, but it means that you've got a lot of work on your hands to make it fit. It's not good enough to throw two people together just cuz you think both are hot.
If you want to match a canon to your OC, it can be done. I've seen several fanfics where this works, and sadly, several fanfics where it's gone horribly wrong. The key thing you have to do is explain why the couple are together, what brought them together and why they stay together. You also need to do this without trampling over established facts, such as a character's prejudices for example, and editing the character in order that they like your hideous Mary Sue.
I hate and detest this with the fury of a thousand burning suns. No, I am not saying that you can't have rape as a plot element, but it can't be the whole point of the fic. This shows up in both het and slash, and most people can't write it effectively at all. I especially loath the plot where one character rapes another, which has the result of the victim falling in love. And not tortured, Stockholm Syndrome-esq love, but proper love. That is not realistic and is frankly insulting to rape victims.
Here's a link
to an author's opinion of rapefic, which pretty much matches my own, and explains just why it's offensive.
5. Lack of attention towards grammar and spelling.
While it's true that not everyone is perfect at spelling and grammar, you ignore them at your peril when writing a story and putting it out for the whole world to see. If you really can't spell or use grammar, then it's a good idea to get a beta to go thru your story and check for such things. Generally, betas are better off found online, rather than you appointing your best friend to do it. A beta can also check for faults in the story, such as lack of consistancy, and make suggestions on how to fix it.