* CompleteMonster: [[InsaneAdmiral Captain]] Hisashi [[ItsAllAboutMe Kurokawa]] of the Imperial Japanese ship ''Amagi'' is a brutal [[LovesTheSoundOfScreaming sadist]] and [[AxCrazy madman]]. Allying with the monstrous Grik, Kurokawa kills thousands when his ship destroys the Neracca home in an attempt to get at the USS ''Walker''. [[BadBoss Torturing his own crew]] at the drop of a hat, Kurokawa also gives one tenth of them to be devoured by the Grik in exchange for his own life after a defeat, before managing to climb the ranks by offering the Grik Japanese military technology. [[MadScientist Conducting horrible experiments]] on the Grik, Kurokawa frequently orders their suicides for his own failures and consistently tries to kill both his enemies and innocent people. [[spoiler:When he captures his ArchEnemy Matthew Reddy's pregnant wife, Kurokawa tries to compel her assistance by threatening to have her comrades raped and later orders all prisoners besides her executed. [[ChronicBackstabbingDisorder Treacherous to the end]], Kurokawa dies scheming how he will ally with Reddy before betraying him after Reddy thinks he is trustworthy]].
* DesignatedVillain: ''Contre-Amiral'' Laborde is demonized by the Allies for [[spoiler:sinking SMS ''Amerika'', which was operating as a hospital ship and fully loaded with wounded troops at the time,]] in "Blood in the Water", but what's never really acknowledged is that [[spoiler:''Amerika'' had actually fired the first shots on the orders of her ScatterbrainedSenior captain, and was trying to [[RammingAlwaysWorks ram]] Laborde's battleship when he gave the order to return fire -- all this [[ISurrenderSuckers after formally yielding to Laborde's demands, i.e. attacking under the flag of truce]], which ''is'' an extremely serious war crime]]. Laborde is a FrenchJerk and a bad guy for sure, but any one of the Allies would have done the exact same thing in his place.
* HesJustHiding: Given the number of people lost at sea in explosions or sinking (and how occasionally characters thought dead do turn up alive, like [[spoiler:Tony Scott]] in ''Storm Surge''), it's nice to hope others survive their apparent deaths from time to time, like with [[spoiler:Sato Okada]] and his crew in ''Iron Gray Sea'' or [[spoiler:Perry Brister]] in ''Winds of Wrath''.
* JerkassWoobie: Gravois is a pretty sleazy and ruthless guy but it can be hard not to pity the sheer scope of what he's put through in ''Winds of Wrath.''
* LikeYouWouldReallyDoIt: Inverted with [[spoiler:USS ''Walker'' herself]] in the final book, "Winds of Wrath". According to the afterword, every book reader Anderson talked to just assumed that [[spoiler:the ship, and perhaps Captain Reddy as well, would make the ultimate sacrifice and be KilledOffForReal]]. In the end, though, he just couldn't bring himself to do it.
* MoralEventHorizon:
** That racist asshole who raped a 'Cat in book two. ''Walker's'' other enlisted men lynch him for it.
** If destroying ''Neracca'' Home in "Crusade" didn't do it for Kurokawa, sending hundreds of his own men to the Grik cook-pots to save his own hide absolutely solidified him as one of the most vile villains in the series.
** Walter Billingsley wades into this territory when he [[spoiler:abducts Rebecca, Sandra, Sister Audrey, Silva, and Lawrence]] and blows up the dock's fuel reserves, killing 17 people. He steps up a notch by ordering the captain of the ''Ajax'' to fire upon two Lemurian ships because the female Lemurian captain of the frigate dared to speak to him and concocts a plan to "dispose" of all hostages but Rebecca and have the captain and the men loyal to him executed by a KangarooCourt for "firing upon a defenseless ship".
** Don Hernan presumably crossed it long before the series started, what with him being a Blood Cardinal, but his ColdBloodedTorture of [[spoiler:Fred Reynolds and Kari-Faask]] in the months between "Firestorm" and "Iron Gray Sea" confirms beyond any doubt that he's an irredeemable monster.
** Gravois crosses it in "Blood in the Water" when he [[spoiler:hands Laborde's Alliance prisoners over to Kurokawa, along with a League battleship, in a bid to lure the Allies into an apocalyptic battle that will wipe out both sides and ensure nothing can challenge the League]].
** General Allegria, Don Hernan's son, absolutely plows over it in "Pass of Fire" when he [[spoiler:rounds up hundreds of El Corazon's children, turns them into ChildSoldiers, and throws them at the Allied forces as CannonFodder to protect his own Blood Drinkers]]. Needless to say, this is treated as a ThisIsUnforgivable moment by Blas and [[spoiler:most of the city's population]].
* {{Narm}}: The Dominion is so over-the-top evil and hammy that it's hard not to laugh at some of its atrocities, especially when the heroes invoke AndThatsTerrible (which they do a ''lot''). The same is true of the Grik, but they can get away with it thanks to being a different species and thus having BlueAndOrangeMorality.
* NightmareFuel: How much time you got?
** At the climax of book one, Matt and his crew team up with the Lemurians to board a Grik ship. The battle is horrific enough (though not without several [[SugarWiki/MomentOfAwesome badass exploits from humans and Lemurians alike]]), but then everyone goes belowdecks and find a "brig" where ''Lemurian captives are being '''butchered alive''' for food, and the survivors are ForcedToWatch.''
*** They're perfectly willing to do the exact same thing to ''each other'' if there are no prisoners around. And they're so damned ''casual'' about it...
** And then there's the twisted, torture-happy sonsofbitches of the [[ReligionOfEvil Holy Dominion]].
** "Superlizards" in the jungles of Borneo.
** "Flashies," basically man-eating tuna that act like piranha. Also the plesiosaur-like gri-kakka, also man-eaters. Basically, falling in the water is a death sentence.
** The [[NamesToRunAwayFromReallyFast Mountain Fish/Leviathans]]. ''Maelstrom'' opens with [[spoiler: Princess Rebecca Anne [=McDonald=] having a nightmare about her ship being attacked by one of these huge bastards, only to wake up and find that her ship really is being attacked and ''devoured'' by one. She and O'Casey are the only survivors]].
*** USS ''Mahan'' ran into one of these west of Java following [[spoiler: Kauffman's mutiny]]. With half of her boilers already knocked out, ''Mahan'' could only run away at 16 knots, ''and the damn thing still almost caught her''. It finally gave up when the destroyer reached shallow water.
*** The first one that chased USS ''Walker'' took a dozen 4-inch high-explosive rounds and a pair of depth charges. They still don't know if they actually killed it or just pissed it off. Silva still claims bragging rights either way, though.
*** At least active sonar will scare them off...
** The “greater dragons,” enormous allosaurids that are the apex predators of South America. [[spoiler: The Dominion even uses shackled ones as war beasts, and they are ''not at all'' tame]]. What’s worse, even the elephant guns used by Imperial militia volunteers, who are used to taking down dinosaurs, are a NoSell against them. Only heavy artillery will bring the damn things down.
--->'''Capt. Blas-Ma-Ar USMC:''' ''Cease fire! We just pissin’ it off! RUN!!!''
----