* AlternateCharacterInterpretation:
** Amberley can be seen as enjoying Cain for his abilities and occasional company, but some lines make her look like a ClingyJealousGirl, notably when she mentions she'd have found out if Cain was really trying to seduce women he met.
** Similarly, it is possible to interpret Cain's monogamy after getting involved with Amberley as simply his self-defense instincts kicking in: "When dating an Inquisitor, it ain't over till ''she'' says it's over!" (His comment about only having room in his life for one lethally dangerous woman comes to mind.)
** Cain is a DirtyCoward, a LovableCoward, TheSoCalledCoward, or went through those steps along the way towards his retirement.
* BadassDecay: Averted:
** The Cain novels are more or less the only ''Warhammer 40K'' media that ''convincingly'' continue to portray Necrons as horrific monstrosities to be feared. Cain has only pulled off one win out of three encounters with the Necrons (and only by blowing them up from orbit), as opposed to his constant success against just about everything else. They are also the one threat thus far that he has adamantly refused to stand and confront, reputation be damned.
** The novels are also some of the few 40K works that manage to juggle presenting ''all'' of the main factions as badasses. The one exception is the Eldar, which haven't been featured except for Cain's mentions of his time as a prisoner of the Dark Eldar, which he still has a bit of PTSD over.
** The Orks are a more... interesting case. While they are more often than not the "Original Antagonists" that Cain is sent in to fight only to later stumble upon the real threat (Necrons or Tyranids), they ''are'' considered the comic relief army in 40K, and the 597th are considered experts at fighting Orks, so it gets played with a little. They get their DayInTheLimelight in ''Death or Glory''. In the beginning of that book he mentions that Orks are considered a bit if a joke in-universe... but then he notices the veterans are taking the threat very seriously indeed.
* DarknessInducedAudienceApathy: Skillfully averted. WarIsHell, but Sandy Mitchell humanizes it so that you actually care (see for example the sequence in ''Death or Glory'' where Cain enters a town orks have passed through), and the humor in the series offsets the grimdark nicely.
* DiscreditedMeme: For many fans, typing '''HERO OF THE IMPERIUM''' after every instance of Cain's name.
* FunnyAneurysmMoment: If you read in continuity order; a CallForward in publication order. In ''Death or Glory'', Jurgen is [[HardHead mostly uninjured by a blow to the head]], and Cain says, "It would probably take a bolter shell to crack that thick skull of his." In ''For the Emperor'', Jurgen's skull is fractured near-fatally by... a bolter shell that glances off his helmet.
* GeniusBonus: Overlaps a lot with the {{Shout Out}}s on the main page.
* IronWoobie: Issues of self-esteem are the least of humanity's worries in the Warhammer 40K universe and so it's never emphasized in the books, but Cain has enough trust issues and paranoia to disturb [[Literature/TheDresdenFiles Harry Dresden]], and a self-esteem so low that it should be measured in the negative. He goes through his entire life convinced that no one could or should care for him personally, unable to connect with people on any meaningful level, unable to ever credit that he's a remotely decent person or so much as pat himself on the back for the ''billions'' of lives he saves, and terrified to trust anyone with his thoughts, lest he be shot for cowardice and deceit. The closest this ever gets to a LampshadeHanging is when, at their second meeting, Amberley gently implies that she isn't fooled by his facade and suggests that he could try being himself. He practically shits his pants thinking that she's a psyker and is going to have him killed, and he never actually takes her into his confidence even after a century of romance. That's ''sad.''
* MemeticMutation: One of the few memes originating from Wiki/TVTropes: it has become tradition to write '''[[FakeUltimateHero HERO OF THE]] [[TVTropesWikiDrinkingGame IMPERIUM]]''' after Cain's name whenever he appears on another page.
* {{Squick}}: The Mechanicus genestealer-breeding experiments in ''The Greater Good'' (where convicts are implied to have been forcibly impregnated by infected test subjects) are squicky enough to visibly disturb a visiting ''Tau''.
* TakeThatScrappy: In ''The Last Ditch'' the Tyranids deploy a number of Pyrovores, a notoriously badly designed unit which more likely to blow up itself (and a huge chunk of its allies) than anything useful. Cain exploits this fact by killing them when they're near the Hive Tyrant, and they end up winning the deciding battle of the war for the Imperium.
* TheyWastedAPerfectlyGoodPlot: Fairly early in "The Greater Good", Tau ambassador El'hassai suggests an exchange of observers between the allied Imperial and Tau forces and suggests Cain to be the human representative in the Tau fleet. Instead of agreeing and the book being about Cain fighting alongside the Tau, he nominates ambassador Donali to go instead and sticks with the Imperial force for the rest of the book. As a result, the scene on the cover of Cai back-to-back with a Fire Warrior facing down a swarm of Tyranids [[CoversAlwaysLie never happens]] and the Tau go on to play almost no part in the rest of the story.
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