assyrian has got me started on thinking about one of the standards of fanfic - I think of it as the familiarity phenomenon.
Readers do not want something that upsets them. They want to feel they have some "control" over a plot, which is why they get upset when a character dies in fanfic, or an author tries something they find repulsive. Readers want to read the same story, over and over, which is why we keep SEEING similar forms of the same story.
It's one of the reasons why almost all fanfic ends on a positive note (unlike real life). Readers want a compact, happy ending. They don't want to be shaken out of their comfortable world.
Doubt it? Just look at Harlequin romance novels. A huge ton of those sell, and it's not like the story is always that different. A beautiful woman is going to be misunderstood/taken advantage of by a rich, gorgeous guy. The misunderstandings - which are never her fault - rear up between them, threatening to drive them apart. In the last ten pages, the guy will develop New Age syndrome, and suddenly all the misunderstandings are cleared up through one conversation. And they kiss and the world is a pretty place.
the sad thing is that i'm considering writing one of these... just write to spec!
I think this is a reflection from real life. Life is hard, and people want to know that things will work out okay. They project quite a bit of themselves into their favorite characters, which is why they don't want anything TOO bad to happen. Some torture is fine, but they like being reassured that everything can eventually be fixed.
The familiarity phenomenon basically works from "write what you know." It's why High School AUs are so popular - many of the readers are currently in high school and can relate more. It's why we see so many "runaway" stories, since a lot of us wish we could run away and find where things are better. Same with all the angst, and suicidal girls being rescure by bishounen characters who are madly in love with them. There's tons of wish fulfillment going on.
I laugh every time I see a person requesting a specific "type" of fanfic - "vampire Sasuke!" or "Duo as a Girl!" They basically want to read the same story they've already read before... or have written in their head.
Familiarity is one of the reasons that there's so many spec-type writing and why it's so sensational. It's rare that an "original" idea breaks out. Most authors - including the insanely popular Rowling - write using archetypes. While
assyrian was talking about "benchmarks" for the characters, it's really about the type. We don't fall in love with Fuji or Seishirou themselves... we fall in love with the manipulative bastards they are. We fall in love with a archetype, and we have expectations on how they're going to be handled.
Oftentimes I'm asked what "type" of character I prefer. I'm shallow, I admit it - I tend to go for the frosty bishounen that supports the lead. It's rarely a surprise to those who know me best which character I end up obsessing about.