I got an idea for a story about three or four weeks ago, but I haven't started writing it yet, mainly because I need to figure out how to start it off. 

I do, however, have the plot (or, at least, the basic idea of one) written down. Here it is:

OC (21) lives with her older brother (24). Hebworks everyday except Saturday and Sunday, leaving beforebdawnband getting back home after 8 p.m. Due to this, OC is left to her own devices for most of the day.

This is a problem, because, having decided not to attend college, she is always home alone. She has two best friends who Vista when they can (and who actually did decide to attend college), but other than that, it's just her.

OC doesn't like being alone so much; she feels awkward. Because of this, she is almost constantly moving around - washing dishes, doing laundry, sweeping and vacuuming, making sure their two cats are fed - dping anything she can to keep herself busy.

On one of her brother's days off, he tells her he's thinking about asking his best friend to stay at the house so that she has someone to keep her company while he's at work. 

OC has never actually met her brother's friend, so she's wary around him at first, but she gradually warms up to the idea of having him around.

[Normally I at writing plots/descriptions, but i think this one turned out pretty decent]

Now, for anyone who decided to read this (thank you, btw), I need help with two things:

1. I don't know whether I want this to be a fanfiction or just a regular original story with someone famous portraying one or more characters.
2. Regardless of which one I do, I need someone to portray the best friend. I can figure out my OC and her brother later, but right now, I'm going to focus on her brother's friend.

In my head, he is someone who gives off a kind if friendly older brother vibe, protective but not overly so. He knows when to joke and when to be serious. He's good at comforting people when they need it and gives great advice (for example, if OC were to trust him enough to tell him something personal, or if she's nervous or unsure about something, he would know just what to say or do).

Read that again, then close your eyes and think. Who do you imagine as her brother's best friend?

Before I even knew for sure I wanted this to be a story, I was picturing Yixing, but just recently I've started picturing Johnny. I brought it up to my friend, and she suggested Luhan.

I'm curious to hear who you guys think would fit the role. (Choices are not limited to the three mentioned above.)

Also, please don't choose based off of popularity. I wantbtobread guys to actually think about this.

Thanks in advance to anyone who wants to help!