Disclaimer: Why do I always have to say this? Zim is not mine.
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By lunch, Zim had simply decided to ignore Ked and to just focus on his plan. Dib, meanwhile, was still suspicious.
"Gaz, that new guy is weird. He's always angry, and throughout all of class he didn't do anything but glare at Zim. I'm telling you, something's up. Ked knows something, and I'm gonna find out what. I'm gonna-"
Dib shut up when Gaz turned to glare at him. "Dib I'm on the last level of my game and if you make me lose because of your obsession with Zim or Ked or whoever, I'm gonna make sure you regret it for the rest of your delusional life." Dib shut up and went back to watching Zim.
Suddenly, out of nowhere, a raw hunk of meat (which may or may not have been already decaying) sailed through the air and struck Zim on the back of his head. He screamed as the meat burned him, running around in circles. As he managed to finally peel the meat off, his first thought was, obviously, that Dib did it. He immediately jumped right at Dib, ready to tear him apart when another piece of meat struck him in the PAK, bouncing harmlessly off the metal device. Nevertheless, Zim instinctively turned around to see who threw that one, and saw Ked, standing on the table, clutching yet another piece of meat in his hand ready to throw it. Dib noticed with mild interest that Ked's hand was steaming where he held the meat.
Zim leapt at Ked viciously, who dropped the meat in surprise. "Alright, what's the big deal! Who are you!" Zim shouted.
Ked grinned. "Why Zim, I'm surprised you don't recognize me, even after so many years."
Zim thought for a moment, then it hit him full-force. "YOU! Ked! From the academy! But I thought you were dead!"
"No, I'm not dead. I was exiled from the Empire thanks to you! I don't know what you did or how you did it, but I just know that somehow you're behind my banishment. And I swore I would get you back for that! So now, here I am, after finally having tracked you to this filthy planet full of filthy pig-things, I am ready to finally exact my revenge and take from you the same thing you took from me all those years ago: your life! Prepare to die!"
And with that, Ked tackled Zim to the ground. Due to the fight being in public, neither Irken dared to use any technology. Ked was exceedingly vicious and pulled no punches. However, Zim had been trained by Zak, and had additional experience from fighting Dib, and so was able to gain the upper hand. He eventually managed to (just barely) pin Ked to a table while he reached over and grabbed some of the cafeteria sludge that no one knew the identity of. Ked kicked Zim off him and got up to tackle Zim again, but Zim took that opportunity to hurl the sludge at Ked. The glop hit Ked right in the face, who screamed in pain as the sludge immediately began to dissolve his exposed skin. Ked screamed in agony and fled the cafeteria, managing to shout "This isn't over, Zim! I will get you back!" before running out through the doors.