The Authority/WMG

Jenny Quantum is not the latest in the Jenny reincarnation cycle, but an Alternate Universe version of Haruhi Suzumiya.
It's stated in the comic that she is far, far more powerful than any previous Jenny. Anything pointing to her being a Jenny can be explained by the fact that she believes herself to be a Jenny, and thus has altered reality to fit that.
 * Alternatively, Haruhi is Jenny Quantum, in an alternate universe where the Jenny cycle has never been noticed before.
 * Of course, ''Authority: Revolution" implies that Jenny Quantum created all the Jennies before Jenny Spark from scratch because she went to the Doctor's Garden of Memories and thought it was pretty neat.

At the end of Watchmen
Heck, it's not like Dr Manhattan couldn't cross the Bleed if he wanted to.
 * Hell Manhattan may have created the entire Wildstorm universe, self defence systems like the Jennies and Elijah Snow, possibly super-humanity as a whole were created to prevent someone being able to pull off a trick like Ozymandias' end game.
 * Except, of course, worse things than Ozy's end game have happened in the Wildstorm universe. Ask the Finns.
 * An early theory (going back around the time Watchmen ended) was that Dr. Manhattan went on to create the DC Universe, or possibly the original Charlton comics universe. These universes are notably "simpler" then the harsh reality of his own world.

Jenny Sparks was madder than the Weatherman
With all her protestations of not wanting to be involved, she built herself a pretty nasty powerbase before her end. Many powerful forces went dead or converted to her cause when she was around.

The Midnighter is Dexter Morgan
Bear with me on this one. His entire memory was erased when Bendix finally sent the team on their first mission (which only he and Apollo survived), so we have no way of knowing Midnighter's history. In his solo series, it was implied that Bendix chose him because he was already a serial killer who was set off by some unbelievably traumatic event.