Madman noun – A person who seeks out very dangerous or foolhardy adventures with no apparent fear. Eccentric and madman are semantically related. Sometimes you can use "Eccentric" instead a noun "Madman".
Caligula devolves from an eccentric libertine to a madman who is cursed with the occasional moment of lucidity and in his delusions of godhood tortures and kills his sister Drusilla, the one woman he loved (while she's pregnant, no less).
Most of this comes from the company being run by an eccentric madman who was then replaced by a sentient computer program, both of which took far more pleasure in just running inhuman experiments on test subjects than actually trying to apply the knowledge from those tests in any meaningful way.