* ArcFatigue: Abe's journey to discover the truth about his existence. It goes on for several issues, with him waffling back and forth about his purpose and [[ContemplateOurNavels general navel-gazing]] with very little resolution. It takes the end of the Hell on Earth series to get a conclusive answer regarding his origins and he still expresses uncertainty about his goals.
* EnsembleDarkhorse: Kate Corrigan was this back in ''Hellboy'' and gets bumped up to a lead role here. A few minor agents have built up enough reader love to make them the Dark Horses in this title, including [[{{Everyman}} Giarocco]] and [[CrazyAwesome Howards]].
* HolyShitQuotient:
** ''Everything'' about "King Of Fear", the end of the ''Plague of Frogs'' cycle. Liz's vision of the future, the return of the sub-terranean race, who have [[VillainTeamUp allied themselves with the frogs,]] the return of the Black Flame and finally, the worldwide breakout of the Apocalypse, kicked off by the fact that Comicbook/{{Hellboy}} has just ''died'' over in his own book.
** The finale of the ''Hell On Earth'' cycle. [[spoiler: The Titans, Anum's fallen brethren who created the Ogdru Jahad, have risen from beneath Hell. Abe's coming back to Liz and the Bureau... but Iosif, Panya and Kate are dead. One of the Ogdru Jahad was loosed upon the world... but at [[HeroicSacrifice the cost of his own life]], Johann ''[[DidYouJustPunchOutCthulhu killed it!]]'' Oh, and Varvara's taken over Hell...]]
* MagnificentBastard: Memnan Saa again.
* MyRealDaddy: Mignola isn't shy about emphasizing the contributions of others to the BPRD series. In particular, he cites longtime series writer John Arcudi as the prime architect of many characters, including Ben Daimio. Some characters have also been "gifted" to others to write whenever they wish - BPRD agent Ashley Strode is Cameron Stewart's, and Simon Anders will only be written by Fabio Moon and Gabriel Ba.

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