(Some of this text is reprinted from John Scalzi.)The Old Man's War series (former trilogy) takes place in a universe in which humans are a relatively small species struggling for survival and worlds to colonize. They are in constant battles with other alien races. In order to fight back, human soldiers are heavily modified through cloning, genetic and cybernetic technologies. These technologies allow for the central focus of the trilogy; that humanity's armies are primarily made up of elderly from Earth's developed nations whose consciousnesses are transferred to genetically enhanced, youthful clone bodies to fight for human survival in the galaxy.As the namesake novel, first published in 2005, explains: Elderly Earthlings sign up ten years in advance of leaving the planet. But what happens to those who don't live that long? Their genetic code is adapted to create Special Forces soldiers, who are physically adult from birth, are specially souped up for combat, and have mental technology allowing them to communicate at faster speeds (this makes it hard for them to deal with "normal" people, since norms are slower thinkers and Special Forces soldiers aren't constructed for tactfulness and social skills).John Perry and his wife, Kathy, signed up, but Kathy didn't live long enough to make it. Imagine John's surprise while in battle one day to see his wife's face.... on a Special Forces soldier named Jane Sagan.In The Ghost Brigades (2006), a rogue human scientist turns traitor against his own race and becomes a hero to another. The Colonial Union create a clone and try to download Charles Boutin's memories into it. When it doesn't work, Jared Dirac is allowed to become a typical Special Forces soldier. But things don't go quite according to plan...In The Last Colony (2007) and Zoe's Tale (2008), companion novels taking place during the same time period, but with different narrators, John, Jane and their adopted daughter Zoe get invited to be in charge of a new colony, Roanoke. There's all kinds of things that they haven't been told about the place, though...The Human Division (2013) takes up the where the series left off, dealing with the fallout, bringing back old characters and introducing new ones. Released in weekly e-episodes via Amazon etc, the novel-in-stories features cover art for each chapter by John Harris. A second "season" has been confirmed.
This series provides examples of:
Aborted Arc: The werewolves of Roanoke never come up again after the first conflict with them. Zoe's War goes into a bit more detail about them, though.
Anguished Declaration of Love: No in-plot examples, but Master Sergeant Ruiz mentions having had it happen to him; characteristically, the reason he brings it up is to make the point that if you're attracted to a fellow soldier, the time to talk about it is not when you both should be concentrating on not getting killed.
Artificial Limbs: Actually, whole artificial bodies in Old Man's War, but also soldiers regularly have whole limbs replaced and regrown using nanobots.
Ascended Extra: Harry Wilson, one of the last three survivors of the Old Farts in Old Man's War, returns as an extra in The Ghost Brigades, and is a major protagonist in The Human Division.
The Bad Guy Wins: How The Human Division ends, with the conspiracy succeeding in driving a permanent wedge between Earth and the Colonial Union.
Batman Gambit in multiple ways: In The Ghost Brigades, Charles Boutin's attempts to gain revenge on the Colonial Union and repeated adapting to changes in plans; In The Last Colony, they're all over the place—The Colonial Union's attempt to destroy the Conclave, John Perry's plan to defeat Admiral Eser, and the most convoluted, General Szilard's "plan" to bring the Special Forces into the open.
Bi the Way: Several of John's fellow recruits turn out to be bisexual. It's dealt with in exactly as matter-of-fact a manner as the trope suggests.
Black Comedy: And plenty of it. This is, after all, a war story.
Bloody Murder: CDF soldiers can ignite parts of their SmartBlood at will. It's mostly used to deliver a satisfying demise to alien mosquito-analogues, but Jared comes up with some more... ambitious applications. The Human Division has further application of this, with a captured CDF officer using it to incapacitate her torturer.
Brain in a Jar: Mentioned in The Ghost Brigades as the CDF punishment for refusing direct orders. The Evil Conspiracy in The Human Division uses them to turn spacecraft into drones, with the added bonus of making it look like the Colonial Union is behind things, thanks to the aforementioned punishment.
Charles Boutin in The Ghost Brigades perfects the storage and downloading of mental copies, though it has kinks.
Not to mention the process of moving from your old body into your soldier body upon enlisting in the CDF.
Bullying a Dragon: The CU's plan to break the Conclave turns into this. They humiliate the Conclave by using Roanoke as bait for their unified fleet and destroy it. Somehow they missed that nearly every ship in the fleet was the flagship of each member race and give 412 member races a personal kick in the nuts. So they get the internal strife they wanted, but it's largely over whether or not to just kill us all off in retaliation. Turns out, though, that it worked out better than it seemed it would when it happened, as explained in the Conclave chapter of The Human Division.
Casual Interstellar Travel: Averted due to the CU monopoly on skip drive. Trade, communication, and most of all colonization are strictly controlled.
Chekhov's Gun: Weaponized SmartBlood and the use of trees climbing to avoid hostile guns in The Ghost Brigades.
Child Soldiers: Ghost Brigade soldiers are rarely older than fourteen, due to the unusual nature of their creation. Despite being utterly deadly, barely-human killing machines, the lack of emotional maturity does show on occasion.
Cloning Blues: The Old Man's War trilogy features extensive cloning, where the clones usually aren't brought to consciousness before having a progenitor's consciousness installed.
Technically, none of the CDF bodies are clones because they are based on highly modified versions of the original DNA.
Colony Drop: In The Ghost Brigades, one of the techniques used by the Special Forces to cover their tracks is drop an asteroid on it. They've apparently used this trick often enough to become very good at making it look like an accident.
They actually drop asteroids (with some pre-placed seismic sensors) for underground recon.
Congruent Memory: In The Ghost Brigades, the reason copying Boutin's mind into Jared doesn't work at first is that he's a blank slate with nothing for the mind to connect to. When he starts having experiences that relate to Boutin's (enjoying one of Boutin's favorite foods, visiting a place Boutin has been), parts of Boutin start to reappear.
Empty Shell: The Obin. They were uplifted to give them intelligence but not individual self-awareness. Their own word for their species means "lacking." They border on The Soulless due to their drive to acquire consciousness and the utterly inhuman debt they feel towards Boutin for working on how to provide one for them.
Actually a subversion (discussed in the first book). Since you can't go faster than light, you drop your ship into a nearly-identical analogue universe while their virtually-identical version of the same ship drops into your original universe. For pragmatic purposes, it's teleportation: the physicists tend not to dwell on the fairly mind-boggling ramifications when laymen are around.
Fictional United Nations: The Conclave, intended by its creator to put an end to the incessant territorial warfare between the Loads and Loads of Races and divvy up colony worlds fairly. First mentioned in The Ghost Brigades, The Last Colony and Zoe's Tale deal with an attempt by the Colonial Union to sabotage it. After determining that the alien in charge had the right idea after all, especially since the Union's success immensely pissed off 412 different species, he and Zoe help the Conclave reform and pull the Benevolent Alien Invasion above.
Green-Skinned Space Babe: The members of the CDF, their skin is photosynthetic, they are all in perfect physical shape, and they are possibly even altered to look sexier than their normal genetics would allow to encourage bonding and to exploit the natural human tendency to treat good looking people better.
Ruiz calls out minorities during his spiel at the start of basic training... then yells "BULLSHIT! You're all green!" (He has N-Word Privileges, being Hispanic.)
Grey and Grey Morality: And plenty of it. Interestingly, it's often the Colonial Union (i.e., humanity) that comes across as a slightly darker shade of grey, though it's a very close-run thing.
Hates Everyone Equally: Ruiz can come up with a reason to hate everyone except John (whom he finds a reason to like, which scares him).
Hero Antagonist: General Gau. He's a honorable man with few personal ambitions who is working hard for peace.
Humans Are the Real Monsters: Specifically the Colonial Union, which is often of the magnificent variety. It keeps Earth, its source of colonists and soldiers, as an isolated, technological backwater. It strictly controls communication and travel between the colonies themselves. Even set against a backdrop of hundreds of feuding alien species, very few of whom are nice guys, humanity stands out for its merciless tenacity. That said, the series does note that a lot of the more bastardly tendencies are justified by the more horrifying tendencies of the opposing species. For example, most (hostile) alien species are depicted as eating humans and other intelligent species. Humans don't. And mostly humanity is just absolutely, completely ruthless, far from actually malevolent, which is actually required for survival because humans are one of the newest and smallest species on the galactic stage. Anything else means extinction, at best, or being farmed for meat, at worst.
Lilliputian Warriors: One of the alien races fought in Old Man's War are almost exactly like humans, except they're only an inch tall. They're depicted as being hopelessly outmatched by the human military in ground battles, but at the very least evenly matched in space battles. Tiny ships can only have tiny weapons, but they're also too small to aim at properly... and they're very, very cheap.
Longevity Treatment: The CDF's main selling point. Rejuvenation treatment via consciousness transfer to a genetically enhanced body is only available to military personnel—and the minimum age for joining the military is 75.
Roanoke, though it's both deliberate and temporary. Lampshade Hanging ensues when, after he figures out what's happening, the main character chews himself out for having missed the reference.
Before the CU monopoly on skip drive "Wildcat" colonies were fairly common, most failed within a year.
Low Culture, High Tech: The Consu give the Rraey a sensor far in advance of any race's ability and understanding that can predict the exact location a ship will exit hyperspace in, which they only bother to use for it's intended purpose. When Perry manages to get the "owner's manual", it's enough to revolutionize human understanding of hyperspace theory and allows major breakthroughs in the following books.
Loyal Phlebotinum: The standard CDF assault rifle is designed so that it won't fire except in the hands of its authorized operator. In training, that's weapon's owner. In combat, that's any CDF soldier. This comes in handy more than once, but becomes a problem in The Ghost Brigades when the villain disrupts the authentication process, leaving the attacking soldiers stuck with guns that won't fire for anybody.
Machiavelli Was Wrong: And the Colonial Union gets itself into some serious trouble as a result. But then manages to get out of it without a war.
Meaningful Name: The Last Colony has a few spoilerish examples: Roanoke colony and Perry calling himself a Commodore play it straight. Trujillo, the ambitious politician, is a subversion, since he's one of the good guys.
Mental Fusion: Special Forces are raised with an active BrainPal from "birth", allowing them to share their senses, thought, emotions and memories. While not a Hive Mind, it creates a powerful anti-self pro-group type of bias in them, and it's very unpleasant for them to be denied integration.
Our Werewolves Are Different: An intelligent, humanoid yet hairy species on Roanoke are called "werewolves" because that's the closest thing they resemble. As far as we know, they don't shapeshift.
Physical Fitness Punishment: On the platoon's first day in training, Master Sergeant Ruiz makes a point of finding a reason to give each and every person a twenty-kilometer run, with the threat of everyone having to do it again if one person takes longer than an hour. This is partly so everyone knows where they stand with him, and partly to make the point that, with their new technological enhancements, they all can run twenty kilometers in an hour, among other feats.
People Farms: One possible fate of a human colony conquered by aliens who think human meat makes good eating (which, unfortunately, is most of them).
Pro-Human Transhuman: The soldiers of the CDF. During boot camp one guy asks why they're bothering to defend baseline humanity when their new bodies are the next step in human evolution. Sergeant Ruiz tells him he couldn't be more wrong, all the alien DNA in their genomes makes them sterile and thus an evolutionary "dead end". In fact one of the reasons for the advanced enlistment age is so most of the recruits would have grandkids back home they would want to protect from baby-eating aliens.
Psychic Link: Created through BrainPal technology for soldiers.
Puny Earthlings: The reason why the Colonial Union no longer uses unaltered humans as soldiers.
Scary Dogmatic Aliens: The Consu. Curiously enough, though, that dogma makes them less dangerous than they might be - they could easily steamroll everyone else in the galaxy, but they prefer their battles to be religiously-significant or at least sporting (i.e., fair) instead, to the extent that they'll even equip their troops with technology similar to that of their enemies, whomever that might be (though technology levels don't vary too radically between species, except where the Consu are concerned).
Sense Loss Sadness: In Ghost Brigade, being pulled out of Integration (a type of Mental Fusion) has this effect, as does having the BrainPal shut off. Given that SpecOps troops are literally raised by their BrainPals, and spend pretty much their entire lives integrated, it's less 'sadness' and more 'crippling, mind-destroying shellshock'.
Settling the Frontier: The Last Colony and Zoe's War both focus on the difficulties facing settlers creating a new, secret colony.
Shoot the Dog: How the Colonial Union justifies the various atrocities it commits. Much of the series involves deciding whether or not its actions are necessary for humanity's survival. Turns out that not only are they unnecessary (despite what initially seem like some pretty decent justifications), they're actively harmful.
Space Amish: The Colonial Mennonites in The Last Colony, though they don't seem to actually have an objection to technology per se, but simply object to excess technology, and that's why the CU sends a large group of them to Roanoke, which is likely to be cut off from the rest of the CU for a very long time, meaning that coping with lower tech levels would probably be necessary at some point.
Space Elevator: On Earth, but operated by the Colonial Union. A notable example because even though a Space Elevator could be built in the real world, the one the C.U. operates isn't physically workable (its anchor is in too low an orbit). This gratuitous violation of physics indicates to astute Earthlings that the C.U. is keeping secrets from them...
Spiritual Successor: Although it is definitely its own novel, Old Man's War is fairly clearly an homage to Heinlein'sStarship Troopers, without descending into the Anvilicious territory that makes the older book a little jarring.
Star-Crossed Lovers: Harry and Danielle look like they're heading in that direction by the end of The Human Division.
Starfish Aliens: Just about everything in that isn't a human. There's only one race of aliens mentioned who are roughly humanoid, and they're about an inch tall. The most advanced race in the known universe look like giant, blade-armed stingrays.
A few like the Whaidians and Covandu are physically different from us but seem quite comprehensible in terms of motives and culture. Even the Consu have understandable (if odd and frightening) values. Hell, the man-eating Rraey even have celebrity cooking shows!
Strawman Political: Interestingly played with in Old Man's War. On one of their missions, John's squad gets a new recruit in the form of an ex-politician, who initially seems to perfectly fill out the military sci-fi stereotype of the obnoxious, sanctimonious bleeding-heart liberal. However, it soon turns out that his political views are at least somewhat correct - his problems (in the form of a raging Messiah-complex and blindness to practical concerns) are purely a matter of personality.
Super Soldier: The Colonial Union's soldiers require only a few hours of sleep, can hold their breath underwater for several minutes, and have a fantastic Healing Factor.
And that's just the basic soldier, their Special Forces have even better reflexes and reaction times, not to mention being born that way. And there are even some who can survive in hard vacuum.
Of course, as the drill sergeant in the first book points out, the Union isn't giving its volunteers brand-new, youthful, super-tough bodies bristling with genetic and nanotech enhancements because it loves them: it's spending all this money because all the other sapient species out there have their own Super Soldiers, and baseline humans would be totally outclassed.
Taking You with Me: Dirac's nasty surprise for Charles Boutin after the latter took over Dirac's body.
How Captain Coloma deals with the Erie Morningstar.
Telepathy: Possible to be done on anyone with a BrainPal, by anyone with the right clearance.
Theme Naming: Special Forces soldiers have the last name of a famous person in science and philosophy (or science fiction, for the Gamerans).
To Serve Man: Some species, the Rraey in particular, find humans to be quite tasty.
Transhuman Aliens: The Gamerans. Human brains, but everything else about them is a bizarre space-monster. They're specialized military forces, but the other facet of their existence is to get at least one branch of humanity out of the fighting-for-limited-real-estate game by letting them live free in outer space.
Tree Buchet: Used by Special Forces soldiers to escape an enclosure guarded by automatic turrets that lacked the ability to aim up. Justified by it being a treelike lifeform on an alien planet, more elastic than actual trees.
United Space of America: The Colonial Union. English is the main language, the military is dominated by former US citizens, and the influential, older colonies are populated by many descendants of American (and other first-world) colonists. But subverted in that all the new colonies are populated by people from countries and regions that can't support their populations (thanks to being kept that way by the CU), which amounts to most of them being from Africa and Asia (especially India), though Norway is also mentioned as being unable to support its population, and so is a source for colonists.
Weirdness Magnet: Whilst it's never quite clear whether he's blessed with exceptionally good luck or cursed with exceptionally bad, John tends to be at the centre of a lot of improbable coincidences.
What the Hell, Hero?: Lots of 'em, in all sorts of different directions. Let's just say that this is a series that believes in giving weight to many different viewpoints in many different situations and leave it at that.
Wiki Walk: The Special Forces BrainPal does this to explain concepts.