Good and Evil

Syrum

I lead Mark further and further down the hallway.
"First, we need to break into Fall's study" I planned.
"Why?" Mark asked.
"Just trust me"
"Alrighty then"
Farther down the hallway was a door with a "Do Not Enter" sign on it.
"I think that's our que to enter" I said sarcastically to Mark, gesturing to the sign. We cracked the door open a little and peeked in. It seemed clear, so we entered. We sneakily looked around for anything that could help us. There were all sorts of the tools and weapons that Fall had in the binder on her desk in the other room. Many were covered in dust and looked sorta rusted, but there was one that was almost sparkling because it was so clean. It was some kind of syringe filled with a substance I didn't recognize. There were smudges in the dust next to it. It was a note saying, "Jackaboy, this is very useful, use it. Trust me."
I reread the note more than once, trying to comprehend that this random person wanted me to inject this unknown substance into myself without knowing who they are. However, something made me trust them. The fact that they called me 'Jackaboy' comforted me because Sammy always called me that and I missed the name.
I think they wrote more in the dust, but ended up wiping it off because there was an illegible smudge under the rest.
"Well, it can't get much worse, so may as well just use it." I said mostly to myself.
"No!" Mark yelled, clearly concerened, "What if it kills you?!"
"It's okay, Mark. It is clearly not cyanide or anything of that sort, so I doubt it's anything deadly."
"Fine, but if you die, I'm gonna kill you"
"Ha, your logic doesn't make any sense"
I took the needle and flicked it to make sure there were no air bubbles, then I put it to a vein in my arm and stabbed it in. The needle wasn't huge, so it didn't hurt that bad. I pushed down the end of the needle, pumping in the substance until it was gone.

Mark's POV
Jack had just finished injecting the liquid into his arm when he stood up straight. He looked at me dead in the eyes and dropped the needle. The crash echoed throughout the room and scared the crap out of me so much that I visibly jumped.
That was when Jack started teetering. It looked like his balance was leaving him very quickly. His eyes partly closed and he fell towards me. Thankfully, I broke his fall and dragged him away from the broken glass. I laid him on the ground with his head in my lap. I was looking down at him when his eyes rolled into the back of his head and his eyelids closed the rest of the way. He was still breathing, but his muscles went limp.