Ciaphus Cain is an entertaining character. He's basically Blackadder but in 40k. With all the common sense that everybody else in the setting utterly lacks.
One of the very first things we learn about him in the first book... he does NOT want to die. And with that detail in mind, he is aware that over-eager commissars are very prone to dying heroically... usually a strangely long distance from the front line. So, he does the unspeakable... he does NOT be over-enthusiastic, and he actually tries to be a good leader to the men of the Valhallans. Purely for self-serving interests, you see.
Dude is utterly convinced that he is the greatest of cowards. Ignoring that he earned respect from a Dark Angel for his ability to hold his own in a duel... nay, ignoring that he once one-vs-one'd a KHORNATE CHAOS MARINE IN MELEE and was NOT utterly demolished. Granted, he only defended, long enough for his loyal companion to line up a melta gun and blow away the berserker. But he spent the entire fight aura farming. AURA FARMING. Because, in his head, he NEEDS to maintain the heroic reputation, or else he will be, I don't know, forcibly assigned to a suicide mission and that means striking heroic poses and making one-liners, all to hide that he was basically bricking himself in terror.
Never mind that that same HERO OF THE IMPERIUM reputation keeps getting him sent to the same suicide missions he is really desperately trying to avoiud.
Also, even after his death of old age (something that is very rare for anybody in 40K, never mind an active duty commissar), the paper pushers won't change his status to deceased, because of how many times he has seemingly come back from the dead.
Ciaphus Cain is just that entertaining a character. His series of novels are easily among the best of 40k's collection. Must read recommendation from me.
As an aside, one of the Ciaphus Cain novels actually had the distinction of showing what the Orks are like to the ordinary humans of the setting. The ones who don't get to experience the funny meme green machines with their funny accent. And to ordinary humans, Orks are genuinely scary. So kudos to Sandy Mitchell for managing to depict that properly.
And as another, less related aside... AAAAGH! Typing when you have a great hobby knife-inflicted cut on the pad of your finger SUUUUCKS!