Grammar and Plot: There are a lot of mistakes with commas. Commas are important because they make sentences flow and they're there for a pause in a long sentence. They also prevent run-on sentences.

What Not to Do:
"Fine" I said throwing my hands in the air and scampering off to my wardrobe and looking through the clothes I had
"Want some help Dallas?" Niall asked walking over to where I was standing and slightly grazed my arm which sent shivers up my spine, I snapped out of it when Niall held out the cutest outfit ever
"Thanks Ni!" I squealed and ran into the bathroom and chucked them on and walked out and getting a nod in approval from Niall
"You look good, now let's go Louis is waiting" he said pulling me out the door and outside to his white Chrysler and headed to Louis's.

What to Do:
"Fine," I said throwing my hands in the air, scampering off to my wardrobe, and looking through the clothes I had
"Want some help, Dallas?" Niall asked, walking over to where I was standing, slightly grazed my arm which sent shivers up my spine. I snapped out of it when Niall held out the cutest outfit ever
"Thanks, Ni!" I squealed, ran into the bathroom, chucked them on, and walked out, getting a nod of approval from Niall
"You look good. Now let's go. Louis is waiting," he said pulling me out the door, outside to his white Chrysler, and headed to Louis's.

See how that looks. Just make sure to look back at it before publishing it. It'll help if you read it aloud or had somebody else read it before publishing it. Another thing is you have a problem with capitalizing some words. An example is you'll have damn by itself. Here's what you want to have Damn. It's just minor things that can help this story better. Also, add more details.

Plot and Story Line: It's different... in a way. It's just not my type of story. I like how you have a Niam bromance going on rather than a Larry Stylinson. It's different and unique. I just can't get into it. Maybe others will get into it. Another thing is I'm very confused with what's happening in the story. Everything is happening so fast.

I would give this story a 5/10.

Notes

If I was a bit offensive, please tell me and I'll take your review down. I'm just being honest and giving you tips on what to do and what not to do. I'm trying to help you improve and that's my main goal of doing reviews. I'm not trying to be mean in anyway.