Krom was a failed experiment. He was diagnosed as underdeveloped from the moment of his birth. He was left to die with no PAK. Anj witnissed this, took pity on Krom, and stole him away. She attached a worn-out PAK to him, which apparently gave him delayed capabilities.
Krom never matured mentally or physically, and Anj often has to care for him. She took him with her to Earth on her investigation but left LoLo in charge of him during dangerous parts.
Krom, despite his delays, is seen as a good fighter by the Tallest, as he was actually successful when he accidentally volunteered for Invader training. However, Anj refused to let him become an Invader.
Krom lacks some basic comprehension and social skills due to his defective PAK, leaving him relatively vulnerable. He does consider himself worthy as he is able to trip people up with his unfamiliar behavior. Krom is not much less destructive at heart than a non-defective Irken, but has trouble expressing it because of his trouble speaking and moving. He especially enjoys hanging out with GIR, but without LoLo, he could accidentally destroy the world.
Main article: LoLo
LoLo, standing for Longterm Occupations of Logical Operation, is Krom's SIR, built by Anj as a nanny for Krom. LoLo is very serious and prevents Krom from doing anything deadly.
Zim seems to dislike Krom, but Krom doesn't notice Zim much.
Anj and Krom are like siblings, or a mother and son. Krom relies on her and she protects him fiercely, though at times she speaks over him. He typically is not able to refute this.
LoLo hates his job, as Krom treats him as a plaything.
Krom and GIR enjoy each other, but as seen in "The Trade-Off", the two together are dangerous to the universe.
People rarely notice Krom, including Dib, since he can't attend skool. However, Dib shows no mercy for Krom, either, which enrages Anj.
Like Dib, she hurts Krom when she targets Anj. this is one of the reasons Anj hates her.