Who Am I?

Isaac

"DAAAAAAAAVIDDDDDDDD!" shouted Isaac's mother as she cried. She failed as a mother, she listened to that disembodied voice which resulted in her son, being forever gone. It killed her on the inside, for she knew he couldn't come back. Isaac was only 7, he couldn't have survived the fall into the basement. Even if he did, he would bleed out quickly for only being a small child. 

"You have both succeeded and failed at my task," boomed a gruff voice. "Isaac was indeed corrupted by Satan. He failed at fighting his inner demons, so he became one with the demons. Isaac is still alive however, recovering. In a realm where such power is normal. He does not know why you attempted to kill him so he may shun you later in his life. Be proud, for he will be that Realm's hero. You won't have any memory of Isaac, for it is too dangerous for you and this realm. Goodbye," boomed the once again, disembodied voice. Isaac's mother and the rest of the world have no memories of Isaac…

???: "Marty! We're going back to Remnant! Wait, wrong show… uh, Hi?"

Marty: "Doc, who are you talking to?" 

Doc: "Nobody Marty!"

Jokes aside, back to Remnant

Isaac recovers from his state of unconsciousness. He's in a white, firm bed. 

"I forgot how this felt… to have a bed again that is," Isaac says as he speaking to himself.

"Ahh, you're awake young boy. May I ask what you were doing in the Forest, during initiation too, if I must add. calmly speaks a man with grey(or gray)hair." (I use Grey for the color/pigment, while Gray is used for names.)

This sudden voice causes Isaac to morph into the Lost.

"I can still see you. Calm down young man, no one is here to hurt you in any way, shape, or form. My name is Ozpin." states the man. Knowing this bit of information allows Isaac to calm down and return to being himself once again.
"What were those black things…" questions Isaac.
"Those are creatures that are commonly referred to as Grimm. They have different names for each type, but only one to four types should be in the forest," states Ozpin. "Now, what were you doing in the forest, alone, at that."
"I had no choice… all I remember is jumping into the basement and falling. It was… scary." replies Isaac.
"Interesting. Team RWBY, come in," as he calls for them, four girls walk in. "As you girls have found him, I need you to watch over him. Someone must've lost their son. Be it in Vale or the other kingdoms. I am sorry, but this is something you cannot refuse. No one in Beacon knows about him and his semblance other than you four." Ozpin shortly leaves after he finishes, leaving Isaac with the four girls.

"Uhhhh, ok. That just happened." Said Yang, who is currently not amused
"...as long as he doesn't touch any of my books, he's fine." mumbles Blake
"I'm going back to our dorm to figure out what just happened." states Weiss, who is currently trying to process everything.
"Welcome to the team?," Says Ruby. "I guess I'll take you there since everybody left us." 
"Ok."  Isaac says. He immediately gets out of bed and takes Ruby's hand while smiling. For some reason, Ruby seems a lot like his mother… before she tried to kill him that is. Ruby's face warms up a bit and smiles. "He's too cute…" Ruby thinks to herself before walking to the dorm...