I was surprised to find that he'd gone in such a similar path the first time, when he really hadn't known he had powers. His current reign of terror seemed to be a response to the trauma of that first experience and what the Authorities did to rein him in, but apparently not — he got super violent and bloodthirsty before as well.

His dad had no Ability
We have no direct evidence to support this, but trope-wise, I would not be surprised if John's dad either has a very potent ability or is in a leadership role of some shadowy organization. Explains how John won the power lottery in a setting where this does seem to be genetically determined, and why he's away so much.