Superman[]
Brainiac's arch nemesis and source of interest. Originally, he was supposed to meet Clark alongside Kara, but after believing him to be weak, he deemed that he should be taken care of and considered him of no use. It's only after witnessing his unique abilities that Brainiac changed his mind. From the moment they met, after learning that the evil machine was the one who destroyed the planet Thanagar, by using Kara as a living weapon, to openly telling Superman he will be a weapon as well, to the reveal he destroyed Krypton, Brainiac is the only one to truly earn Superman's hate.
Kara Zor-El[]
Brainiac's former enforcer and adopted daughter. While not much is known about their relationship, Brainiac had raised Kara in a solitary life and taught her until she became a powerful warrior that was willing to make worlds bend to their empire. Kara considers him strict, as she implies that he doesn't let her eat certain foods. However, in truth, He actually brainwashed her hole life In order to make her a un-questionable, ruthless warrior for his empire and he is also emotionally manipulative in his "affectionate moments".
Supergirl ends Brainiac's reign of terror
And while Brainiac does acknowledge to Kara that he genuinely loves her as a daughter, he feels the need to purge himself of it so that he may continue to build the Kryptonian Empire, and he brutally attacks her to do so. Eventually, all relations between the two were permanently broken after Kara realized he had been brainwashing her ever since they met and was a morally-bankrupt, callous monstrosity, which culminated in Kara destroying him herself after helping Superman thwart his invasion of Earth.
Jor-El and Lara Lar-Van[]
Brainiac worked with Superman's parents on the Kryptonian High Council. Brainiac has a very negative opinion of Jor-El, calling him weak with "ambitions so small, they could fit in a cradle," and said that one of his goals is to make sure his empire will be different from what it was when Jor-El was alive. It is unknown what opinion, if any, Brainiac had on Lara.