One of the first things later writers changed was making Jason a human being who was possessed by a demon. In other words, something that was different was changed into something that was, at least in comicbook terms, ordinary.

It's not an absolutely clean break, but basically the dividing line between the Demon stories that are worth reading (and, yes, I include my own in this definition) and the ones that are not can be recognized by whether or not the Demon speaks in rhyme all the time. Kirby gave us a transformation spell, to summon Etrigan, and that spell was a few lines of doggerel. Kirby bridged from the verse into Etrigan's normal speech by having the Demon speak his first few lines after the transformation also in rhyme. This became an affectation several writers applied to Etrigan all the time, and, like so many such errors and affectations, it became canon. When I wrote the Demon in ACTION COMICS I reverted to Kirby's pattern, and found myself having to fight to keep it that way. One highly placed editor at DC even told me I had to change it because "we can't say Kirby got it wrong!" I had to pull out the bound volumes from the DC library and show people how Kirby had done it, and, astonishingly, some were still unconvinced! (Part of the problem, it became clear, lay in the fact that many thought it was Alan Moore who had made the change, and, then as now, Moore's stuff was considered sacrosanct.) I won my battle, but the next time Etrigan appeared he was rhyming again.