Martin said that the group loved comic books and superheroes but wanted to approach the material in a "grittier, more adult manner than what we were seeing in the '80s". He cited the series' "sense of history" as a strength and expressed frustration with the retroactive continuity of mainstream comics. Martin also felt that the multitude of sources for superpowers in comics strained suspension of disbelief when taken together, and he believed a single plausible source was needed. Snodgrass suggested a virus, which allowed for the superpowered Aces, the "monsters and freaks" Jokers, and a high death toll. Snodgrass and Martin also developed the card based terminology, and Milan developed the pseudoscience of the series.