Title: 9.5/10

The title is really good. It is unique, interesting and flowed nicely. It sounds slightly poetic and gives the reader a hint about the storyline. The one problem I have with it is that now that I've finished the story, I'm slightly confused as to why you used the word 'Devil' if both Mark and Jackson are demons. Are you referring to the Devil in the story and saying that the Devil's decisions ultimately ended up with the two falling in love? Or do you mean the these two demons have found love and now aren't 'black' as in having a heart of stone.

Description/Foreword: 8/10

The first part of the foreword summarised their personalities and the setting well. 

However, the second part of the foreword put me off a little.

1) The size of the text. I think that this should have been in a larger text size, because it is an important part of the description.

2) I found some issues in how the second part flowed, in terms of writing style, word choice etc.

Here is the original:

One day, they got into a big fight, and they were both punished. But the punishment is bigger than they though. What will happen when they'll have to do the punishment together. No one ever thought about that...It's going to be a disaster.

The issues I found with it:

-The first line is past tense, the second is present, the third is is future, the fourth is past and the fifth is present tense. This was very difficult to read and process. Of course, it is normal to swap the tenses a bit in the foreword, however, too much can be strange.

-'But the punishment is bigger than they thought.' The 'is' is present tense, and then the 'thought' is past tense. It can either be: 'but the punishment is bigger than they think' or 'but the punishment was bigger than they thought.' Also, I think 'bigger' doesn't really suit the sentence, perhaps you should use 'worse' instead, as that flows better.

-'What will happen when they'll have to do the punishment together?' This line just didn't sound right. If you want to stick to the rhetorical sentence, it might sound nicer if you write it as: 'What will happen when they are punished together?' 

-'No one ever thought about that... It's going to be a disaster.' It sounds better if you say: 'Nobody ever thought about that... It's going to be a disaster.'

Plot: 11/15

The plot at some points was unique and at other points, very cliche. Personally, I dislike most fantasyAUs, however, I'm going to ignore that for now. The first problem I found is that the 'two people hate eachother, are forced to live together, fall in love' plot is very cliche. The next is that there were too many subplots which became slightly overwhelming. 

I found the first two chapters a little plain, however, when you started writing about their reactions to common human objects, it became very funny and humorous. 

I think it was a good idea to add a hint of Taeny to the plot, as most fanfics avoid having female characters. Even though this was fantasy, it added a realistic element to your story.

Character Development: 8/10

You didn't really place an emphasis on character development, however, I could still understand the characters. I think this was helped by the fact that your characters where quite typical, rather than complex. This worked for you story because usually to have complex characters, the story has to be very serious or very long. I think that because the characters were slightly predictable, it lightened the mood of the story.

Writing Style: 15/20

Personally, I found your writing a little hard to read.

There were moments where there was so much text that it overwhelmed the reader. 

Your writing style seems to be the type where everything that is happening is dictated to the reader. This is hard to do, and in most cases, like yours, it becomes a bit boring. It felt like the words were written exactly how your brain was thinking at the time.

I suggest that once you finish writing each chapter, go back and edit through it. You can take out large chunks of text that are unnecessary to the plot. Most people hesitate to do this, because it isn't very fun to write thousands of words and then cross out most of it, but it will really help improve the flow of the story. Also, I suggest you use a variety of sentence lengths. Yours are generally all the same length.

For example:

Mark went straight to the couch, waiting for Jackson. But Jackson wasn't coming, so he closed his eyes a little. And that little became a very long nap. When he woke up, he was covered with a blanket, and  had a pillow under his head. The clock showed 20:00p.m. and he wandering where could Jackson be and why was Jackson taking so much care of him.

I would rewrite this as:

Mark laid down of the couch, waiting for Jackson. When he didn't come, he closed his eyes a little. Or so he thought. When he woke up, he found himself covered with a blanket, and there was a pillow beneath his head. Confused as to why Jackson would take care of him, he glanced over at the clock. 20:00p.m.

Spelling, Grammar and Diction: 20/25

Generally, this section was alright, and it was mainly the writing style that affected the score. Your writing is very colloquial, and because of this, the grammar was a little sloppy. Sometimes, the sentences you write aren't grammatically correct or are incomplete, and although the reader can still understand what you are saying, it gets a little frustrating to read.

Your spelling is almost always correct, and their were only a few issues: eg. 'he was wandering where Jackson could be' should be written with 'wondering'. Your word choices are generally repetitive, and you may repeat a word several times in a paragraph. This stops the flow of the paragraph. 

I found that sometimes, you missed a full-stop/period or maybe you misses a word or two. However, there aren't any places in the story where there are  a lot of issues, thus, I can't really take a paragraph from your story and edit it, like I did above.

The main thing is just to proofread it and this should be fine.

Personal Enjoyment: 8/10

I generally dislike , but this one was okay to read. I didn't really like how you had a lot of subplots and your writing style was a little tedious to read. Other than that, it was a great story.

Final Score: 79.5/100