There were only a few mistakes I caught on the description.
You used the past tense when it wasn't really necessary.

Original: He's always ready to make Jongin contented...
Suggested: He's always ready to make Jongin content...

Original: Afterall, he have always loathed Eden.
Suggested: Afterall, he has always loathed Eden.

I also had to take away points for not having a foreword. Having a foreword is always important because the foreword is what readers go to when the description didn't completely pull them into the story. 

Appearance: 4/5

I liked your fan art!

Plot: 13/15

Nice plot, but it was a bit confusing to me.  

Originality: 15/15

Grammar/Spelling: 11/20

There were a few mistakes I caught while reading this story. What kind of confused me is how you worded your sentences.

Chapter One.
Original: ... but unfortunately, he had to wear always the same clothes.
Suggestion: ... but unfortunately, he always had to wear the same clothes.

Original: He was feeling like a thief.
Suggestion: He felt like a thief.

Chapter Two.
You tended to throw in a lot of excess comas.

Original: He had turned around a few times, but he saw no one, so he just walked faster, causing Kyungsoo to complain.
Suggestion: He turned around a few times and so no one, so he began to walk faster, causing Kyungsoo to complain.

Original: Sometimes people joked about them, saying they were twins, but it wasn't like that, of course.
Suggestion: Sometimes people joked about them, saying they were twins, but of course it wasn't like that.

Then you used the wrong verb tense.

Original: He run, run, and run...
Suggestion: He ran, and ran, and ran...

Original: Why Taemin loved so much that world?
Suggestion: Why did Taemin love this world so much?

Chapter Five.
Another wrong verb tense use.

Original: Please, at least come to watch me leaving!
Suggested: Please, at least come to watch me leave!

Original: "Take care of you."
Suggestion: "Take care of yourself."

Original: His legs moved on their own accord, and soon he was running on the grey dessert, gasping for hair, praying for something, praying for a poor human's life.
Suggestion: His legs moved on their own accord, and soon he was running on the grey dessert, panting for air; he prayed for something, prayed for a poor human's life.

You also had a small typo there for 'air' x) 

Characterization: 9/10

I was a bit confused with Jongin's true character. One moment he's convincing himself that he loves Kyungsoo and decides to stay with him, but in the next scene, he's kissing Tao and saying I love you and even ends up running away together. 

Flow: 9/10

During the story, some parts seemed so long and dragged out, while some parts seemed way too rushed.

Overall Enjoyment: 9/10

I really did enjoy this as much as I did with Horizon, but I was quite confused at times...
I really do want to understand this whole Eden and Edge thing. I know Taemin explained it in the epilogue, but it kind of just made things more confusing to me xD 

Total: 78/100

Reviewer's Notes: Sorry, dr3amer is currently packed with requests, so I decided to help her out and review this story for her. Hope you don't mind ^^