Hey guys, da ShadowWolf is back! Sorry it's been a while since I last updated, my Skool has really been piling the homework on. Well, this is Chapter Four! I'd like to thank everyone who has followed my story so far and been leaving reviews, it's appreciated, so please continue to do so. Oh, and for those of you who are curious, the "mysterious illness" Zim has contracted, Lupitis, is pronounced: LOO-py-tiss. Time for the disclaimer, and then the story can continue! I (sadly) do not own Invader Zim, all characters, rights, and aspects of the show belong to Jhonen Vasquez. So then, without further ado, here we go!

(flashback) Dib's P.O.V.

It was a few more days before Zim came back to Skool, and when he did, he had changed. I gave him a very wide berth, not only due to the strange behavior, but also to the fact that, as much as I hated to admit it, I was more than a little scared of him after what had happened at the base. I've started archiving the changes I see about him in my computer.

The first of the changes that I noticed in him were subtle differences in the way he walked. The cocky march he normally exhibited was replaced by a hunched-over sulk, that made him look like he was constantly sneaking around. He walked much more lightly, too, at times I could have sworn he was gliding. At one point I watched him walk through a bed of dry leaves without making a sound.

Another change I noticed in him was his appearance. Over the course of about two weeks, he visibly gained weight and muscle mass, and he's grown a bit larger. Those zipper-like teeth of his got sharper, and grew in length. He's also started wearing a hat lately, just a red baseball hat, and while I'd like to know why, he doesn't seem stable enough to confront.

He's been having strange mood swings as well. For instance, just the other day he was sitting by himself outside during recess, completely calm, and one of the balls some of the kids were playing with rolled by him. He was asked to throw the ball back, but instead of doing so, he threw the ball onto the roof of the school, walked over and punched the child who had asked him to throw it, and turned and sat back down without a word.

His voice has also changed. At first it just wavered between his normal voice and the wolfy one every so often, but now it largely stays wolf-like.

The strangest thing I have noticed however, is what he's been eating. A few days after his return, I walked into the cafeteria to find him sitting alone at one of the tables, eating steak. Raw steak. He wasn't even eating in a civilized manner. He was scarfing them down, tearing them to pieces, tossing them in the air and catching them in his mouth, oblivious to the fact that the entire cafeteria was staring at him in horror. I got the courage to ask how he was even eating that stuff, but in response, he gave me a look that wouldn't have been out of place on the devil himself. He's eaten raw steak every day at Skool since then. He's like some kind of wild animal…

There were other incidents too. During his first week back, he ripped a door off its hinges while opening it. Three separate times. Another of the incidents was when he destroyed one of the bookshelves in the Skool library. No one knows if it was accidental or on purpose. I wasn't there, but I was told that it was just pretty normal and quiet, and everyone was absorbed in their studies, and then there was the loudest crack, followed by a huge crash. Everybody looked up, and there was Zim, standing over a fallen bookshelf. Torn pages and splintered wood were everywhere, and Zim was just standing in the middle of it all, sneering. As soon as he looked up and noticed the stares, he just snorted and left.

One of the more recent episodes happened near the end of his second week back. He was using the electric pencil sharpener, and was taking quite some time about it. One of the kids in the short line behind him decided he had had enough, and told Zim to hurry up. Zim stopped, and removed his pencil from the sharpener. He then ripped three feet of the electric cable out of the wall, and hurled the sharpener through the window, missing the child who had spoken by millimeters, and turned and went back to his seat.

The last incident happened exactly two weeks after his return, and was by far the worst of them. He was sitting by himself during recess, on the bench by the tree, as usual. By this time most of the kids had learned to avoid him, but not all of them. Maybe if those few kids had just been a little quicker on the uptake, the following event would never have happened, but they didn't, and it did.

A group of three kids just walked over to him, and started taunting him and making snide remarks.

"Lunatic."

"Freak."

"Anger Issues."

I watched it all. I probably should have done something, but it's not like it would have helped the matter. In fact, it most likely would have made things that much worse, so I hung back.

I could only look as the kids continued to tease him, oblivious to the fact that although he was still staring ahead, motionless, his muscles were tightening, his claws digging into the bench, that crazed look returning to his eyes.

Without warning, an arm shot out and gloved claws locked around the largest child, the leader's throat. A sickening crack echoed across the playground as Zim's free fist connected with the leader's face, shattering his nose and jaw. He then slammed the kid's head into the pavement and left him there, lunging at the second child.

He grabbed the second child by the arm and threw him against the tree behind him, most likely dislocating the arm and fracturing his spine in the process. The last child he lashed out at with his claws, having now torn through the tips of his gloves, and opened three deep gashes on the kid's face and chest.

As soon as the last child was down, he paused and surveyed the scene, licking pensively at the blood staining his hands. After a moment, he turned and bolted off of Skool grounds, and didn't come back. I never told anyone what really happened to those kids, but I'm not sure why. No one but me knows how they got like that, and all of them are either in a coma or too traumatized to remember, so they aren't talking.

A few days after the last incident, I was sitting on my bed, pondering what to do next.

I need to find out what's wrong with Zim, but I don't really have much to go on… All I have is the name Lupitis… Arrgh! I need more than that to even have a clue as to what's going on! If only I had more information, maybe a database…

I stood up.

Wait! I do! Tak's ship! The ship is still a bit screwy but I can access the database from my computer!

I bolted over to the desk where my laptop sat, and booted it up.

Here goes nothing, I thought, accessing the database.

After a few minutes of searching, I found what I was looking for. I opened the page, and Irken text began to scroll across, quickly being converted intoEnglish. As soon as the translation was done, I read the page aloud.

"Lupitis- A rare virus, the deadliest known disease among Irkens. There is no known cure. Not very much is known about the disease, as all subjects who contract it are banished, as they are too dangerous to remain, and the termination of the subject could cause the spread of the disease. An as yet unexplained side effect of the disease is the ability to consume meat, and uncontrollable cravings to devour it in massive quantities. Lupitis is an illness that first affects areas of the throat, causing sneezing, coughing, and eventually causing the voice to change. The virus quickly spreads to the brain, changing first the behavior, making the subject become aggressive, then changing the physical appearance. The changes in appearance that occur are changes in the stature, large canine fangs growing in, increase in size and muscle mass, large claws on the hands and feet, a thick coat of fur, a bushy tail and pointed ears growing in, and the subject in general taking on a canine appearance. The change is constant, but the disease thrives in the dark, and the change becomes most severe at night. While the disease is the worst in Irkens, it has been observed that most other species can contract the disease as well, albeit with less extreme symptoms. The disease is commonly known by other species who contract it as lycanthropy, or werewolf.

I stopped, there was nothing else on the page. I closed the database, turned off the computer, and just sat there, stunned, as it all slid into place. His behavior, his appearance, his voice, everything. It all made sense. I shook myself out of my shock. I knew what I had to do next. I had to confront him.

The sun had long since gone down as I walked down the road towards Zim's base, and the dim streetlamps were casting eerie shadows in the darkness. I walked slowly, Zim's threat from our previous encounter still fresh in my mind. I was already having second thoughts. When I finally reached the base, I had very nearly turned back several times. The oddly-proportioned house looked as creepy as ever in the gloom.

A cloud drifted over the moon as I approached the front lawn, only adding to the spooky effect. I threw a small stone onto the lawn, confirming my suspicions. The gnomes were off. Despite that, I quietly darted across the lawn, not ready to throw caution to the wind, not after what happened last time. I was just about to ease the door open, but hesitated, a hint of doubt buzzing at the back of my mind. If I'd known what was about to happen, I would have listened, would have turn and run right there without looking back. I thought for a moment, then just decided to ignore it, another mistake. I thought for a moment, then just decided to ignore it. Another mistake.

I slipped inside the bizarre house, and the first sight that met my eyes was Gir sitting in the middle of the room, facing away from me. I was about to say something when the robot cut me off. There was something wrong with the way he spoke, though. His voice was flat and distant. An eerie monotone, devoid of any emotion.

"You shouldn't have come here."

"Gir?" I asked, a bit worried.

"You shouldn't have come here. You'd think you would have learned your lesson after last time."

"Gir? What's going on? What happened?"

"He left, but he'll be back soon. If he finds you, he'll kill you. He isn't the same. He's trying not to do this, it isn't his fault, but he can't help it," continued the robot, as if I hadn't spoken.

"Gir, where is he? I need to talk to him!"

"Have you even been listening? You can't talk to him, you can't reason with him, and you can't help him. He is beyond help."

Suddenly there was the sound of heavy footsteps from outside.

"Too late. He's back. You should hide."

"H-hide? Where?"

"Just hide. Anywhere. Quickly."

I glanced around frantically for a moment, before hiding in one of the roboparents' closets, and closing the door all but a fraction just as Zim came in the door. Peering through the tiny crack, it was all I could do to keep myself from gasping in shock when I saw him. He was still hunched over, but he had a short coat of fur almost the same color as his skin, just a bit darker. His legs were bent the wrong way, much like the hind legs of a dog. His eyes were narrowed, and his teeth and claws much longer and sharper than before, and above his mouth was a small, doglike nose. A long, bushy wolf tail was dragging along behind him, and black, pointed, canine ears to match grew out of where his antennae used to be. When he spoke, his voice was even growlier than it was.

"Gir? What are you doing?"

"Nothing, sir."

"Hmph. Good. At least even you can't screw that up. Report. Has anyone come into the base while I was out?"

I held my breath, praying that Gir wouldn't rat me out. The robot hesitated before speaking.

"No, master. No one entered the base during your absence."

I inwardly sighed in relief. Good old Gir. Then something caught my eye. I squinted, and I saw that I was right. There was something wet all over Zim's uniform. I continued to stare and I noticed the same substance was all over his hands and mouth.

What is that?...

And then I realized.

I think my heart may have stopped beating right then. Time seemed to slow down. I didn't move. I watched as Zim walked into the other room and descended into the base, just barely squeezing into the garbage can. As soon as he was out of sight, I threw open the door and ran like hell, not even stopping to check on the silent, motionless Gir. I ran faster than I ever had in my life. I ran because I knew what that substance was. I ran because I knew why he'd left and what he'd done. I ran because what Zim was covered in was blood.

Cliffhanger! I apologize again for the long wait. I hope you enjoyed this chapter, it took me a long time to write! It was about five pages on Word, and that's a lot by my standards. Please R&R, and tell me if it was worth all the effort! I will try to update soon, see you next time! Invader ShadowWolf, OUT!