Got a couple of fanfic-related ones.
1. If they were in High School.
No. Everybody seems to be doing it, and nobody does it well. These are totally different characters, probably classmates of the author, who just happen to have the names of fandom characters tacked on. They rarely resemble the characters they are supposed to be.
2. Species-swapping.
That is, badly-done species-swapping. I
have seen it done well, but this isn't what I'm talking about. Human characters who are no longer human, without any explanation. Non-human characters who are now human, same scenario. Or, a different version: character is changed to something else, has amnesia, and falls in love with the hero/heroine...who, by the way, has
no idea who they're really talking to, despite very obvious clues. Such as having the
same voice and hair color, for example!
3. Severely underage characters (think 14 years old) falling in looooove, getting pregnant, and "making a stand" to their parents.
Bonus points if the parents are okay or happy with it. Double bonus points if they marry (still 14), raise their child, and live happily ever after without any problems or fights other than a romantic rival who comes along and tries to steal one member of the Golden Couple. No mention of a job for either parent. Some fics blatantly state that the grandparents are overjoyed to support them. Hm, anyone out there think that this might be wishful thinking on the part of the young teenaged author? Hm? Nah.

If anyone likes or writes stories like this, I truly mean no offense. But when I see a story going in that direction, I hit the "back" arrow and resume scrolling down through the list of stories.