There's Something Inside Your Head (Invader ZiM AU)

A Place To Hyde

(CW: death near the end. I don't know if this is necessary and it kinda gives something away, but hey—you don't know who is or how they are!")

Dib had come to determine that he only switched beings once he went to sleep—why Pilot got all weekend was probably because he didn't sleep. Madlad probably didn't even need it, he was so full of chaotic energy. Unfortunately, though, not the good kind.
He ended up skipping class the next day to go to the mall instead. Maybe he went to Hot Topic or snuck inside Spencer's, or went to the food court, or even the Pokéstore... no, actually. He robbed the watch repair place. He wasn't caught, he wasn't seen, he only took two things: both of which were watches (since, y'know, the store). Both of high price, both with jewels embedded into the sides. He just slipped them both into a pocket, and walked out. He didn't care if he was caught or if it was caught on camera; he'd just be gone by next morning.
He did the same in other places: a candy store, Hot Topic, this one place that sold cool gifts but had a defense knife selection in the back... pretty much anything he could quickly get in his pocket that could be of use or interest to him.

By the time skool let out, Dib had left the mall. ZiM was getting home from skool after a day of nothing, only to be met with the scar-covered Dib laying awake on his couch. "Dib!—"

"ZiM, this place smells awful. Have you even cleaned lately?" Dib's nose was all scrunched up.

ZiM at any normal time would protest or throw Dib out, but after the events of the day prior, he didn't dare. "Oh eh, uh... I've just not been in the best mood for that... y'know, ever since my Tallest..." ZiM trailed off, kinda just staring at the floor.

Dib had no Earthly idea what ZiM was talking about. He considered questioning it, but settled on thinking: ever since they what?
And that's when it hit him. It's not like it wasn't obvious, anyway.
"Ah! Right... I'm sorry, little ZiM—you don't deserve that one bit..." Dib sat up. "But! I got you a little somethin' that may cheer you up, hm?"

"Yes?" ZiM got a little closer and sat down, hoping for more cuddles.

Dib instead pulled out some candy pieces and one of the stolen watches. "Some sugar... aaand a time piece! Costs a lot—you could sell if you wanted to."

ZiM removed his contacts and wig, looking down at the items in Dib's rough hands. "Oh... eh, thank you..." he sighs, leaning back.

"Hmm... dear bug doesn't seem too happy about anything today..." suddenly, a second idea came to him—it rather annoyed him, making his anger slowly rise like heat. "If you were abandoned here on this rock with no authority... does that mean you have no interest in preparing the Earth for their arrival?" His voice was shaking, it was on the brink of raising... he resisted, trying not to scare the alien. Right now.

"I... I guess not..." ZiM sighed, leaning back against Dib.

Dib, however, pushed him away almost immediately upon contact. "Not? You guess? Oh, so you just have absolutely no authority to prepare Earth for... no one taller than you?" He growled. "Great. Now how are you going to be able to repay me if I can't even help you?!"

"But you brought me some parts I needed to build a—"

Dib threw up his hands. "Yes, I know, but that was never finished! I just want to help you, ZiM! With literally anything..." Dib grabbed a piece of his hair, just... growling more. His shoulders tensed, his knees came up to his stomach, and his hair was a placeholder for ZiM—he wanted to just grab ZiM and scream at him, but he didn't... he couldn't.

ZiM noticed Dib's exasperation, and shrunk down a bit. "Well... you helped last night with making me feel better..."

Dib un-tensed just slightly, slowly looking over at ZiM. "I did... I did!" He uncurled from himself, grabbing ZiM—like, hug grabbing. "You're still not feeling too great, correct?"