Heartless?

Prologue

The room is almost pitch black except for the control room. The room that has the lever. The lever that has the power to open the portal.
I look over at the portal. It is turning bright orange. That's not supposed to happen. I look over at the control room. There is a man slowly pushing the lever.
"Stop!" I scream. The guy looks over at me and backs away slowly. I run over to him and stand in front of the lever. I cross my arms and glare at him.
"What do you think you were doing? You could have opened it!" I yell. The man looks at me and takes His hand off of the lever. His eyebrows crinkle in confusion.
"How old are you?" He asks. I sigh. Of course I'll be asked how old I am. Every demon hunter is asked how old they are. We never look very old because we are meant to live a longer lifespan than regular people.
"I'm 19 sir." I reply throwing my hands up. The man's eyes flicker with fear. I look closer at the man. He has really pale skin for a human... And his eyes are black...
"You're a demon!" I yell. I grab my rapier. The man summons up black fire. I swing at the man and he quickly dodges my attack. He throws a couple fire balls. I roll under his fire and sweep at his feet. He falls to the ground and his fire extinguishes. I put my rapier to his neck.
"Say your last words." I growl. He breathes heavily. He tries to summon fire but gives up after I press my sword against his neck.  He then looks me straight in the eyes, unafraid of me killing him. 
"Do it." He says. I slice open his neck. I look away and walk back to the control room. I bang my head on the control panel.
'Whooosh!' I look up. The portal was all the way open. I look down at the panels and at the lever. I banged my head right on it...
The walls of the building are getting pulled into the portal. I grab the lever and try to pull it back. It gets stuck in one spot and I back up and plant my feet on the floor, Pilkington harder at the never budging lever.
"Just turn off!" I groan at it. I see the dead demon being pulled into the portal. All the walls are gone from the building and the only thing intact is the control room.
I let go of the lever and run out of the control room and away from the portal. I don't get very far before the portal starts making crackling sounds and I brace myself.
'POW! BANG!'
The portal explodes. I get thrown back into a tree and My head slams against it. I fall over into the ground and close my eyes.
When I open them my vision goes woozy and my ears are ringing. I try to get up but fall onto my face. I groan. This sucks.
After about ten minutes, when the ringing in my ears stops, I try to get up again. This time, luckily, I succeed. I look over at where the portal exploded.
Demons were pouring out, none of them minding me. Probably not seeing me as an immediate threat.
I put my head in my hands. This is all my fault. If I had been more careful this would never have happened.
I put the whole world in danger. I have to fix this. I hear footsteps coming my way.
I look up to see a demon above me. He looks a little shorter than me. His eyes are green. He also has white hair instead of red or gray. He offers me his hand.
"Why are you helping me?" I ask as I look at his hand cautiously. He chuckles and keeps his hand reached out. 
"We aren't all heartless," The demon says. I take his hand and let him pull me up. I jump back a couple feet. I put my hand on the handle of my rapier.
"Who are you?" I ask. The demon laughs. His voice is really velvety and I immediately shake my head after thinking that. I can't think a Demon has good thing about them. They're all bad.
"I'm William!" He says. He looks over me. I grip the handle tighter. Once I stand beside him, I realize that he's actually a good two inches or so taller than I am.
"Who are you?" He asks. I ponder for a moment whether I should tell him my name or not. I don't think it would hurt. Plus, he's been pretty nice so far.
"I'm Ash." I say proudly. He looks at the rapier at my side and realizes something. He scans me over and thinks about something for a minute.
"Demon hunter?" He asks. I nod and go to unsheath my sword. He looks at it pointedly and I decide not to. I keep my hand on the handle but make no move to take it out.
"I'm 20 by the way Ash." He says. The fact that he willingly gave out information about himself stuns me. I look up at him wide eyed and he laughs.
Before I can reply he says "I'll see you Ash!" He teleports off to who knows where. I look around. All the demons are gone. I have to fix my mistake.