1. Go to Sleep
The line is overused, hackneyed, cliché. Of course, this is Jeff's trademark line; but to use it a hundred times in a story? That's already crazy and even much crazier when your OC's the one using it.
Jeff has the biggest fandom (I think); but some people think it's crazy to have a crush on him. Well, what's crazier than your OC acting exactly like Jeff?
Now, every person is unique. Even if you're crazy/mad/insane/lunatic, I don't think you'd be acting exactly like Jeff.
Don't tell me you didn't notice the 'sameness' in JTK fanfics. They're all over Wattpad.
Here's the pattern:
The girl would be Jeff's victim. Then she'd suddenly become crazy. She'd also burn her eyelids and carve a smile on her face. Then next thing you know, she'd be stabbing people too, telling them to go to sleep.
How original. How original.
Maybe you could alter a bit? How 'bout "Sweet Dreams"? Mate, be original. I don't think everyone will automatically become Jeff's female version after a deathly encounter (unless you're good at pulling it off). Right?
Try to at least make your character say something else. Go to sleep is cliché.
Not to Jeff himself, of course. Just don't make him say it after every paragraph. o_O