Basic Trope: A drill sergeant who is torturous to his recruits.
Straight: Bob is the drill segreant of Troper Company. He's rude, abrasive, and yells at his recruits.
Bob is a nightmare of a man who only communicates by screaming, has driven more than one of his recruits to insanity, and is basically the most hated man in the military.
Bob greets every recruit with a series of profane reflections on their ancestry, their courage, their physical prowess, and the chastity of their female relations while they are still at the recruiting office. He regularly phones the mothers of the recruits just to insult them for giving birth to and raising the contemptable creatures he is training. When he is in a good mood he "only" orders a twenty mile a day forced march naked in the arctic and walking over glass shards barefoot. The last miserable, no-good recruit to arrive at the barracks at the days' end is tortured to death for his wussiness. And deservedly so.
Downplayed: Bob is a Jerk Ass, but otherwise not terrible by any means.
Justified: Bob's goal is to toughen up his recruits - it's not his job to be nice or friendly; after all, their enemies won't have any mercy for them in a real battlefield.
Bob the drill sergeant is an incredibly laid-back, friendly guy who is beloved by all of his recuits.
Bob is a nightmarish recruit who is rude, abrasive, and yells at his spineless drill instructor.
Bob is an absolute nightmare of a drill sergeant...until you get out of basic, in which case he's pretty much the friendliest guy alive.
Bob is rude, abrasive, yells at his recruits...and is beloved by them, being A Father to His Men.
Bob enjoys a reputation as a nasty sergeant, but it turns out to be unwarranted.
Bob has a reputation as a nightmare... until one of his recruits breaks and threatens to leave, in which case he supports them and helps them work through the training, helping them succeed rather than let them fail.
He's friendly after basic if he liked you. Otherwise he's still a Jerk Ass.
To an outsider, Bob's men seem to think of him as a father, but if you knew the guys you'd really know they're terrified of him.
He's actually worse.
The drill-sergeant mentality and attitude are transplanted wholecloth into another environment, like a hospital or office.
The Drill Sergeant is a horrible tyrant. Until one of the recruits phones home. Then the mothers and grandmothers of the recruits come out to the base and yell at the drill sergeant and terrify him.
The recruits arrive at base. As they come in to see their trainer, all of the veterans mock them for their fate. The recruits imagine in their minds what a horrible Drill Sergeant Nasty has been chosen for them. Then their worst fears are surpassed. For he isn't a sergeant at all. He is a lawyer.
Zig Zagged: Some of the recruits think of Bob as a father, others fear him.
The drill sergeant is no worse then any other trainer would be.
Bob is the Drill Sergeant Rock of his company - tough, uncompromising but fair to those under his command.
Enforced: Bob is starring in a public-service announcement about the psychological risks of military training.
Lampshaded: "You've been assigned to Troper Company. Looks like your sergeant is Bob Editor. Heh-heh...have fun, New Meat."
Invoked: Bob's CO gives him the laziest and most unmotivated recruits knowing it will set Bob off.
Exploited: Bob is placed in charge of a Penal Battalion; after all, penal battalions are supposed to be unpleasant.
Defied: Bob is eventually told not to do this because it's counterproductive in this specific example.