Brainiacās other half, Lex was also gifted with extreme intelligence, but didnāt use it quite the same way. He quickly turned diabolical, while Brainiac helped those around him. You know how the villain story goes; they get outshined by the hero, decide to steal a human brain to harness more knowledge, implant said brain into head, and finally, attempt to prove superiority by creating concoctions and gases that end all Tweaks. You know, typical.