While the writing quality of your story is good, please note this part of the Content Guidelines:

"Please note FanFiction does not accept explicit content, Fiction Rating: MA, and the rating is only presented for reference."

You should remove all of the detailed descriptions of the physical interaction of sexual or violent nature in the story if you want it to remain at this site, or upload it to a site where "Fiction MA" content is permitted like Archive Of Our Own.

OMG this story is amazing! It's so funny too, I laughed at the end and at what sora did to riku and what axel did to roxas (mainly cuz in this other story axel was lit on fire by roxy) anyway this was awesome no not awesome, amazing!

I just read the description of your other story and it says that he will! This is going to be even more awesome! :-) have a nice day!

Hot. Their dad is clueless

First things first, I sincerely urge you to keep away from the chat speak, unless that is actually how the character is talking in the story as they tell it. If that is the case, than capitalize it, as it comes after the period. So it will look like this: 'BTW'. I also think you should take out the "think that's how you spell it" as it appears to be more of your own insert saying that you think that's how something's spelled. If you're not sure of the spelling, I suggest typing the word into Google and then see what it comes up with for results, and whether it corrects you or not.

A few other things I want to touch on are a couple of sentences that didn't really make a lot of sense to me. This one, for example:

"So me and my brother talk about his old crush Axel until Axel set Roxas' on fire."

Is Sora implying that Axel set Roxas on fire or... is there something on Roxas that he set on fire? I'm a bit confused about that.

This one as well: "Anyway, the thing is I never thought whats gonna be really close to my brother."

I'm not entirely sure what you mean there. I can't figure it out what's being said there at all.

Other than what I have mentioned so far, I think the story is actually not all that bad. I thought you wrote the sex scene quite well, but you have a few errors, such as some mssing punctuation in some places. I would suggest putting the story through a spelling/grammar checker to highlight the little mistakes that need fixing and you should be alright after that.

I wish you all the best on future stories. Take your time writing and have fun. :)