Typical of Zim's egotistical and narcissistic character, he declares his dislike of GIR openly and often, knowing that not only will GIR disregard everything he says, but that he probably won't understand him anyway. Zim's general dislike of GIR most likely originates from his erratic behavior and lack of obedience to his orders, though it is very rare that Zim actually seems to be angry with his SIR Unit.
Occasionally, Zim interacts with GIR as one would with a younger sibling, or a parent with a naughty child. As much as GIR can annoy Zim, he occasionally displays affection towards the little robot through his surprising tolerance and acknowledgement of his robot's feelings, and occasionally watching movies and TV with him. Despite being faulty, GIR has always made his love for Zim all too clear, often demonstrating it in some overenthusiastic manner that frequently warrants unheeded discipline from his master.
GIR couldn't care less about his master's mission (even though it should be his as well) and often opts out of obeying Zim's orders. This insinuating that unlike most SIR Units, which are designed to obey every command, GIR can usually choose whether or not to obey. That being said, Zim often tries to steer his henchman in the right direction, stating it is for the good of the mission. GIR simply counters this with attempts to persuade Zim to relax and have fun every once in a while, despite Zim's frequent refusals to do anything but try to conquer Earth and defeat Dib.
Despite his master's harshness, stubborn nature, and reluctance to have fun with him, GIR is genuinely cheerful and seems to have the mindset that so long as his master is happy, so is he. Which often leads to misguided attempts to make Zim happy, most of which go hilariously wrong. Sometimes he bends Zim to his own will, which allows GIR to get away with some of his antics.
However, their bonds of loyalty to each other are not always strong. In "Nubs of Doom", Zim tried to rid himself of his SIR Unit by replacing him with a new assistant named Minimoose. Although this plan does not go smoothly, Zim does tell GIR that he is "horrible". GIR, however, is not upset by this insult.
Some of the ways that Zim interacts with GIR may be partially explained by the concept of Irken defectives. GIR's non-standard behaviour may be familiar to Zim, leading to his general lenience.
Their relationship can be seen in almost every episode, however a few have critical points in their development:
- Walk of Doom
After realizing that GIR left his guidance chip back at the base, Zim snaps at him. GIR, who just ate his cupcake, begins to cry. Zim misinterprets GIR's tears as a guilty apology and allows the subject to pass. However GIR was merely sad because he missed his cupcake.
Completely disregarding his master's commands, GIR attempts to hug Zim while covered in bacteria.
- Planet Jackers
On occasion, Zim has even looked to GIR for reassurance, likely depending on GIR's happy-go-lucky nature to boost his confidence where it may otherwise fail. When they stop by Dib's house to ask for the temporary use of the Membrane household's telescope, Zim gives GIR a worried glance, to which the robot's reply is a grin, thumbs up, and happy squeak. However, when Zim turns his back, GIR gleefully pretends to squish his head between his forefinger and thumb since Zim is in a distant background.
- Bad, Bad Rubber Piggy
GIR hides dozens of rubber piggies inside his head, hoping Zim won't find them and that he would get to play with them; otherwise they would be tossed into the Time-Space Object Replacement Device. Zim only has to give him a look to reveal the hidden piggies, though a sad look from GIR prompts Zim to allow him to play with them.
- Invasion of the Idiot Dog Brain
When Zim first realizes that GIR is unresponsive, he sounds mildly concerned. However, the mess that GIR makes of the ensuing situation undoes any concern Zim may have had for his robot.
- Battle of the Planets
Zim shows respect for GIR after the robot pressed buttons on Dib's ship, messing up his flying controls. He expresses his approval by admitting that GIR isn't "such a bad evil minion after all".
- Halloween Spectacular of Spooky Doom
When Zim escapes the Nightmare version of Skool, he expresses concern for GIR's safety, saying "I only hope poor GIR is alright by himself".
- GIR Goes Crazy and Stuff
When Zim finally gets around to fixing GIR's behavioral glitch, he shows what may be his true colors, though this is uncertain. GIR tells his boss that he cannot stand him and sees him for the woefully inadequate leader and master that he is. This could either be a result of Zim's frequent ill-treatment of the robot or a change in GIR's personality after being "fixed".
- Walk for Your Lives
GIR is surprisingly helpful and focused in this episode, to a point. He helps Zim get the slow explosion to the Voot hanger but quickly returns to his destructive antics when Zim blames him for damage to the base. When Zim decides returning the explosion to the proper speed is the best course of action, it turns out to be GIR, surprisingly, who acknowledges the danger. Zim disregards his advice.
- Invader Poonchy
When Zim sees GIR's dog disguise lying down with beef oozing out of the zipper, he thinks that GIR has turned into ground beef and cries until the real GIR jumps out from behind the couch.