Is it normal?? help...

Ok, this might sound crazy, or it might not. Let's see.

I'm 18 yrs. Old, and I have custody of my 14 yr. Old little sister. She's in 8th grade and this yr. She met a new boy that moved here. They quickly became friends, and all seemed well...

A couple months ago this boy "asked her out" she kept this from me. But it was blatantly obvious. But I was ok with it anyway, I mean they're still so young, how much could it really hurt? Much more than I thought. This boy had a bad past with his mother; drug use, physical abuse, homeless shelters. Until his grandma took custody of him and sent his mom to rehab. I was fine with this, tho. Everyone has problems, and none of that was under his control, anyway.

But, it turned out to be far more than just that. First, it was his mood swings. Mad one second, happy the next. He always apologized, said he didn't mean it. Then he told my sister about These terrifying nightmares he's had for as long as he could remember. They terrorize him almost every night.

On top of this, he constantly cups his hands around his mouth and talks to himself. He constantly tells my sister he wants to be an assassin and a "god", having enough power to make humans his mere "toys".

But, this is the scariest part. A few nights ago he told my sister there was a voice that promised him everything he wanted, it talks to him like a friend, etc. He calls the voice Ezreal, and apparently it communicates with him through objects. Such as a friend's stuffed unicorn and a picture of a cat. Last night, he told her "Ezreal is here, I can hear his whispers." my sister has never been so scared. The principal at their school had an immediate meeting with his grandma this morning, but I'm still afraid to send my sister to school. This boy is unstable and despises many kids in the class, as he has confided in my sister. He also told her not to tell anyone what he has told her. He said he'd "get" her. He's a master at manipulation, and truly unstable. I don't know what to do anymore.