Nabu is some sort of cosmic child molester.Nabu intentionally lures in young Kent Nelson, and then kills the boy's father so he'll cooperate. He spends years "mentoring" the young child after placing a spell on him that makes him incapable of experiencing pain or grief so he won't be traumatized. It's been established that Nabu has no problem manipulating Kent and playing with his memories. When Kent grows old enough, Nabu begins physically taking over his body. He even uses a spell to make sure that Kent never fully ages. Nabu has been molesting him in secret the entire time. This explains everything... why Nabu was exiled from Cilia in the first place, why he desperately didn't want Kent to learn he could merge with Inza even if it meant reaching his true potential, even why Kent always blacks out and forgets what happens when Nabu takes over as Doctor Fate in the middle of the night. It's probably why they put him in suspended animation in the first place. This picture◊ really seals it.
WMG / Doctor Fate