This is an Invader Zim one-shot story idea that I think is the most accurate portrayal of an ending to the series.
The following is a rough sketch, if you will. It's half a plot explanation/actual incomplete story. You'll understand as you read. You'll get the basic idea. Almost the entire story is here anyway… so… yeah.
The plot is that Dib comes into contact with The Tallests once more and this time his questions bug them so much that they come right on out and tell him that Zim's mission is a fake and to stop worrying about it - that he's too short and stupid to possibly succeed. Also, that his SIR robot is not a real one - one that they tricked Zim into getting instead by calling it "Advanced". They tell Dib that Zim is the most hated being on his planet and was originally banished for destroying a thing of theirs called "Operation Doom I".
That night Dib lies in his bed and thinks about all he's heard. After a while he comes to realize that he's just like Zim - he's the most hated being on HIS planet: Planet Earth.
The more he thinks about it, the more he feels sorry for Zim, surprisingly. All his life he wanted to be a Paranormal Investigator. Wanted to help mankind. Wanted to not be labeled crazy... prove his father that he's not INSANE. No one ever understood. No one cared. Should he have even bothered? What was the use?
Now... now he realizes, although Zim was his chance to prove himself to the world - yet he was shunned anyway, that Zim isn't even a threat. He's not quite intelligent enough to use his weaponry and technology and be done with Earth once and for all. And for what? To prove himself to his "beloved" Tallests. Leaders he trusts. Leaders that hate him. Dib shakes his head and all these thoughts rush to his mind all at once.
"The poor guy," Dib thinks. "That stupid alien! What's the matter with him! Can't he see he's being used!" He exclaims half-angrily… mainly angry at himself.
All this time fighting Zim - all for nothing except eternal bruises from being constantly beaten up - by his own people! Even his little sister Gaz. How he cares for Gaz. He didn't mean to make her so angry all the time - he's just trying to be a good brother.
"Zim's the only one who ever acknowledged me," Dib realizes. He closes his eyes tightly and reopens them.
Kids at school laughed and mocked him. Even gave him those HORRIBLE, painful wedgies!
Dad barely has time off of work - barely noticed Dib... or even Gaz. All he thinks is "my poor insane son" and Gaz as his "funny child!". That sickens Dib.
At least Gaz is nice enough to still eat with him - even at lunch in the skool's cafeteria. She doesn't have any friends either - just like Dib. But it's her choice. She couldn't care less for friends. But this is taking a toll on Dib. After all he's done. All he's tried to do to help mankind... he needs a friend. The closest he ever got was... ZIM. Zim hates him so much he's managed to kill Dib once in an alternate time.
KILLED HIM - and walked off sipping a drink.
That horrible alien! His only friend! What a thought!
Dib tries to shake off his tears. Life was always so cruel to him. He can't take it anymore. What's the point in living anymore even?
He jumps off his bed and takes off his long black jacket. His "neutral face" shirt follows.
"Tak's ship was right," he thinks back, "One day with my personality and it hated itself. It was right..." he shudders a sigh, "I AM a loser."
Without a thought he rushes up a wall and flings his body onto it only to fall back down hard. Inside his body ripples with oncoming sobs. He goes at it again - three more times. His last fall and he starts gasping hard.
"You're pathetic Dib... you're pathetic," his inner voice screams.
He sobs out loud finally and lies there on his cold floor. The room's darkness seems to envelope him. "Oh yeah, " he remembers, "that Gretchen girl kind of cared. Had a crush on me, anyway." He laughs sadly. A crush on him! What a stupid girl. What a stupid LIFE! He sobs some more and curls up into a fetal position. Slowly his cries turn to whimpers that echo in his room. He falls asleep with a tear stained face.
Basically the rest of the story has to do with Gaz discovering him and he tells her what he's found out about Zim - and what he's finally realized about himself. Declaring coldly to her that he hates himself. She keeps telling him to be a man and stop crying. He tells her he can't help it - he's lost all strength and hope in himself.
Finally Gaz gives in and tells him angrily to get into his bed. "Don't worry. I'll tell Dad - he'll be the first thing you see in the morning." As an afterthought, "I promise. Just get some sleep and leave the rest to me."
Dib's final thought is whether he should tell Zim the news from his leaders and that he gives up fighting him... forever. Dib falls asleep.
In the morning his father comes and Dib expresses his true feelings about him to him.
Then he's rushed to the hospital… for inspection on his bruised skin… and for therapy.
After a while Zim discovers him there at the hospital thinking he's up to something for not showing up in class. Dib repeats his story to Zim and Zim quickly calls his leaders who tiredly tell him that yes... his mission is a fake and to stop calling them. That at first it was amusing but now they just wish Zim would stay on Earth and basically never contact them again. "You're not an invader, Zim," Red tells him, "You never were." And they hang up.
"Are you all right?" Dib asks him in the quiet room. Gaz sits nearby on a chair and their father in another next to the room's door.
After a couple seconds a foreign voice comes out of Zim, "I-I will be Dib-Hum... Dib." He sighs softly, "I will be."
At the end, after some more talking, the two look at each other. "Truce?" Dib holds out a hand.
Zim, with a small sad smile, "Truce."
And that's what I have. Oh, btw… the father finally finds out the truth that Zim IS an alien and expresses his apologies to his son. Sorry it's not really complete, per se. It's a rough sketch. At least I'm loyal enough to this site to write it all down. I may do a whole story on it ending with that last "truce" line... I dunno.
If anyone wants to take a whack it at it and use this idea for their own story they may. I don't really care. If someone were to do that - contact me first via email.
Thank-you.