Fan Casting Jack Luthor in Justice League: The Return of Brainiac

During the film, Batman and Superman head to Blackgate prison after a meeting is held with the Justice League about Brainiac's return, and manage to find the cell where Jack Luthor, the son of Lex Luthor, is currently being held behind bars. They tell him about the current situation with Brainiac returning, and, after thinking about it for a moment, Jack agrees to help the Justice League, not because he wants to be on their side, but because he believes that he should be the only one that would kill Superman. After all, it's what his father would have wanted...