
This scene singlehandedly makes this Luthor one of the greatest villains EVER!
And I do mean ever. In any media.
Lex is in an impossible position. Brainiac is controlling his body and has made it clear that when his usefulness ends, he'll die.
Then Lex laughs. He laughs.
With Brainiac asking why he's amused, the door has been opened. Now Lex gets to work using his greatest strength: his mind for business.
Lex asks what the point of all this is, and Brainiac levels with him. He's merely programmed to archive and destroy the entire universe.
But what's next? Brainiac merely says his function is complete. That's it.
Then Lex realizes something: Brainiac's talking about ultimate knowledge. Godhood. But with the universe destroyed, what's the point? Thus, Lex says he has something, the ONE thing Brainiac never had: imagination.
Brainiac's power and mind combined with Lex's mind and ambition make them a perfect match. And Brainiac......agrees. He takes Lex up on it, allowing him to join him and fulfill a new mission: making a new universe.
This scene was Lex's single most crucial business meeting ever. Either make his pitch or be disposed of. But he actually managed to convince BRAINIAC, who lacked emotion or regard for any living creature, to become one with him! Seriously, this is a feat among feats!