I own no characters. I got this idea from a mix of ten billion horror stories and a quote from walk for your lives. "well, there is Zim, but I think he stopped being alive."

Zim was always an egotistical little monster, and that didn't change a bit after he died. If anything, it got worse because he can't even figure out that he's dead.

I don't know why he can't understand death. Or at least, his death. Maybe he doesn't know he was killed in the explosion. Maybe he's still so hung up on his own greatness he doesn't think he CAN die. Maybe he just won't accept what has happened and is trying to keep himself convinced he's alive.
It's been two days, and he's doing a very good job of it.
He does, mostly, the same stuff he did when he was alive. I know, because I've been tracking him all over, mostly, the same way I did when he was alive. I don't think he can actually see me. Which is strange. I'm alive, he's dead. He should be the invisible one, but no.
Nothing is ever normal, I guess, when it comes to Zim. I'm just excited, because tomorrow is Monday and he has to go to school. I can't wait to see the look on his face when Ms. Bitters announces why he isn't in school. I can just picture it. Confusion giving way to shock, and then the ever-present rage.
And then he'll come and yell at me Everything that goes wrong for him is my fault. I'm just going to laugh at him.
And then he'll probably fade away, like most ghosts do when they discover that they are dead. He'll fade out of my life, he'll fade from memory, and eventually he'll just be the alien ghost I found when I was twelve.
What a horrible way to go.

(flashback)

Friday nights were great. Everybody thought so. Sometimes because of parties, sometimes because of movies that were coming out.
But not For Dib. Not for Zim.
For them, Fridays were great because they symbolized another fight to the death. Invariably, after these fights, they would drag themselves home, broken and bloody, but with the sure knowledge that they had won, triumphed against each other, again.
But this one was to be different. This was to be the one real fight to the death. The final one.

The battlefeild for this Friday was to be an old clearing in the woods, a place Dib had once likened to the barrens in IT. There was a creek that flowed to one side, and the place was littered with old tires and the like. Dib was planning to use the river to his benefit somehow, Zim was wondering how much cover he could get if he pulled himself behind the concealing leaves of the trees.
Zim was primarily interested in cover that day. The reason was that he was going to break one of the unwritten rules of their warfare.
He was bringing explosives onto the field.
The explosives in question were a highly regarded bomb recently turned out by the Vortions. Perfect for assassinations and planetary warfare because it would destroy all living creatures, leaving everything else untouched. The one Zim had was small, he expected it to affect about a hundred foot radius. The fuse was set for four seconds, faster than the human could fun, slightly slower than Zim's spider legs could carry him.
Foolproof. The humans would not even have a clue as to how the boy had died. Sure, the trees which were effected would lose a few branches, but that happened all the time.
Zim waited in the center of the clearing, waiting for Dib. The earth boy, he knew, would arrive within minutes, he always did. Then it was jut the matter of luring him in close enough to detonate the bio-bomb.
Dib emerged from the trees, pulling a twig out of the spike of hair. Zim grinned maliciously at the boy.
"Whatever you're doing, Zim, you won't get away with it!" "I will! I will for I am ZIM!" "What are you doing anyway?" "Wouldn't you and your inferior Marines like to know?" Dib glared at the Invader. Whatever Zim was planning, he obviously thought it would be big if it involved the marines.
Nothing for it to get closer and check it out…
(end this flashback. OOOH! YOU DON'T KNOW WHAT HAPPENS!)

Okay, I don't own bio-bombs either. They belong to Eoin Colfer, who wrote the Artemis Fowl books. He is great. I am not.