I was going to write another chapter on plot, but I decided I had something else on mind.
characters and characterization.

There is fics on aff that lack good, original characters.

How many fics have you seen Onew as a chicken obsessed clutz, Taemin acting as a 5 year-old who worships banana milk, and Heechul as some Queen-. Now, I know that this is what they can be like in real life, (Heechul isn't always a . I'm kidding, I love Heechul.) but characters need to be original, or readers can get bored about seeing the same people with the same personalities over, and over, and over, and over...

The same thing happens with OCs (original characters) 
When creating your own characters for your fanfics, authors need to remember a few things.
One big part is:

-Don't create Mary Sues.

What is a Mary Sue you ask?
Well, here:

-Urban Dictionary

In short, a Mary Sue is a perfect character. No flaws, always the pretty girl who the main guy falls for.
And they can get
very
very
annoying.

I'm pretty sure that no one likes Mary Sues. Who likes reading about the perfect human?
Mary Sues aren't realistic. You can't relate to them.

The same goes for Male characters, often dubbed Gary Stus.

To stop yourself from making a Mary Sue, (or Gary Stu) try to remember a few of these points.

- Everyone has flaws, including your characters. Don't forget to give your characters in your story little flaws to show they're not perfect. Whether be they have a cussing problem, not the best in school, or even have OCD or something of that nature. Remember that nobody's perfect.

- Make things hard for your new character. One of the most annoying things about Mary Sues is how easily everything comes to them: fighting skills, special talents, strong relationships, special powers that appear just in time to save the day, etc. If your character has to struggle and deal with real problems your readers will start to feel for her. If she does everything perfectly with no real adversity, they'll start to hate her. -wiki answers.

- Take your time. One of the biggest flaws of Mary Sue stories is that things happen far too quickly. It will probably take a while for your new character to become really close to the idols in the story, or be in a position to accomplish lots of amazing things. Go slowly. You can always write a sequel. -wiki answers.

More tips here.

Catch my drift kind of?

I already touched on unoriginal characters (The Onew/Chicken, Taemin/Banana Milk, Heechul/ thingy) and I wanted to say a little bit more.

So as I said, fics lack original characters. Whether they be existing idols, or your own characters, they need to act, think, and speak like a real person.

If you want to create a realistic character, as you write, think about how one of your friends, or even you would react to a situation that occurs in your fic.
You could even write down some real life situations and think about how each of your characters would think, act, and feel about that. This can help you create more dimensional characters.

Now, there is nothing wrong with using popular traits about people in your stories.
ex.: In real life, Sungmin from Super Junior is known to use aegyo a lot and like the colour pink.
Key from SHINee is known for his diva attitude.

You can incorperate traits such as these into your characters (if you so happen to use Sungmin or Key) of your fic. The only thing is when the traits become over-used and too common. Give your characters other sides of their personalities too. (Sungmin isn't always cute and adorable. He knows martial arts too.)

Another thing, if you write two or more stories starring the same character, who says they need to act the exact same each time. Experiment a little bit, go outside the box. (but not to the point where the character is unrecognizable)

I'm going to add more to this chapter later, so I will see you soon guys. I hope these tips are helping you.