The days after meeting Alder Bickerman
Time passed on for ages, but not at all for Zim at the same time. He fell into a routine with Alder, staying reluctantly when the man had offered and he couldn't take himself back. He didn't know why he stayed at Dib's house, he didn't even know why Alder had offered at all. He certainly didn't know why he said yes, why when the man arranged his old office for him to stay in and got him a bed, he felt more at home than in his previous base. It had already been 2 weeks before his room was almost totally set up. It was only a month more that Zim steadily stopped noticing anything abnormal about his new routine, simply following his new companion around the property, watching as he got after trespassers and people who littered.
Alder's domain reached all the way to the campground, and stretched as far as from the end of the mountains. Most of it was wildlife reserve, the rest little hunting trails and further on was land that others managed. The work was easy and peaceful. Alder simply traveled around on foot most days of the week, picking up trash and filling the bag he carried with him. He also took notes on the environment, and would send the information over to someone who would utilize the data and use it to help the land.
Zim thought his job was fascinating, possibly the far opposite of his own task as an invader.
His pak seemed useless to him after a very short period of time, only fussing about it for the first week and a half before barely bringing it up anymore. Alder happily worked on it, but once Zim stopped joining him and seemed to express apathy, the progress slowed to a stop. Alder had gotten his help one last time to condense it, then had stored it carefully in a larger sized safe he bought for the occasion. Zim hadn't requested any of this, but Alder made sure to give him the code and a spare emergency key, insisting all of this was necessary to help Zim out.
No more pak, and Zim got to find out what it meant to be alive without technology changing everything about his personality and body. Not only did he find out that his pak was causing a lot of aggression and anger, it prevented him from feeling his needs and made him unfathomably ill to move between using it and not, and Alder had no way to charge it. He did fine without it, he noted he was surprised how little he missed it after so long. His only problem became the holes in his back that helped latch it on, and Alder aided him with bandages and covers, Zim often just lightly wrapping ace bandages around his torso.
Every day he woke up and ate a small meal with Alder, then slunk around the house observing all his stuff, waiting for the man to finish his tasks. As more time passed, he had started following his friend more and more.