[Derek]

You are bored. The initial hysteria from his classmates as a result of seeing a zombie had died out a while ago. Now people were fearful, speaking in lukewarm whispers about how they were supposed to get out of this, how they were supposed to survive. Some were also crying softly for food and water, [i]Sucks to be them. Their fault for not being prepared[/i], you smirk. But your irritation has reached a peak. The teacher had been trying to regain order, repeating futilely for everyone to calm down and that they would be rescued soon. But you can see in his eyes that he doesn't believe what he's saying. You glance outside balefully, you wanted to be out there, killing things left and right but instead you were trapped in this measly classroom. [i]Time to do things my way..[/i] You reach into your backpack, and pull out the dagger resting in there discreetly. Walking up to the teacher, you decide to give him one last chance and ask, "May I go outside?" The teacher, the fool he is, adamantly refuses and you unsheathe the dagger, grip him by the throat, shove him against a wall, and stab him repeatedly in the chest. And all the while, you laugh maniacally as his face is twisted with pain and shock. Once he stops moving, you pickpocket all the keys on him, throw the corpse to the side, and gauge your classmates' reactions. They look back, wide-eyed and fearful of what they just witnessed. Some had fled to the very corners of the room, others were hiding under desks, and then there were those that were flat out crying. You grin and address them in a low, threatening tone, "Everyone here now has to listen to me."

One brave soul steps forward and says shakily, "Y-you murdered him! How could you?! Why should we listen to a sick bastard li--"
His words are cut short as you stab him expertly in the throat. He gurgles, blood gushing from the wound, and dies.
You survey the rest of your classmates and ask, "Any more objections?"
This time they remain silent. 
"Good. Now first order of business, no one here is allowed to leave the classroom without my permission. Although," you remind them darkly, "That should go without saying unless you want to be eaten by the zombies outside."
They all glance fearfully at the door.
"Second, everyone should empty out all of their pockets and put all their backpacks up here, on the ground near the teacher's desk. Anyone failing to comply will be," you gesture to the two bodies lying on the ground, "Disposed of."
The class nods fearfully in agreement.
"Good. In addition, anyone who is able to bring me more weapons, food, water, and other useful items shall be rewarded accordingly." 
You stroll to the back of the classroom, noting, satisfactorily, how everyone shrunk back as you got near. You open the door, grab the nearest zombie, and stab it in the head. You fling the corpse to the side of the classroom, eliciting shrieks from your classmates at the sight. You get a tissue and casually wipe the blood off of your hands and dagger.
"And finally," you flash them a cruel grin, "As long you guys obey me, you won't have to worry about any zombies bothering you."