When Thicker Than Water is pushed to its furthest extent, it leads to loyalty to one's entire species. This generally requires at least one other intelligent species around, to prove a contrast from a general benevolence toward intelligent beings. They are compatible, just as people can support their families more strongly while behaving well toward non-related individuals -- but Moral Myopia is also possible, which can cause Transhuman Treachery. A Genghis Gambit may be used to cause unity. And it does not keep members of that race from acting as a Dysfunctional Family outside of crisis. A united front may be seen only in times of crisis, facing down aliens or a natural disaster. Les Collaborateurs with aliens are often particularly hated for this reason. May be a reason why Childfree Is Not Allowed If a species is in danger, anyone who can have children and doesn't will be accused of lacking this. Half-Human Hybrid -- or half-whatever hybrid -- may be regarded as treacherous on the parents' part and untrustworthy on the child's, because of it. Technically, all such hybrids should be sterile, since that's the definition of species but many works ignore that. Super Trope of Ape Shall Never Kill Ape
- In Watchmen, the plot was to feign an alien attack to draw this out of humanity.
- In Children of Men no children have been born for more than 20 years. Whenever Kee's baby cries it sparks an instant and almost universal reaction of "must protect" or cessation of all hostilities among total strangers. Only one army officer to tries to capture them for personal gain.
- In Jack Campbell's The Lost Fleet novel Invicible, the spider-wolf aliens know that the Syndics and the Alliance were at war, and regard the fleet's charge to Midway as their "helping our brother-enemies against our not-brother-enemies", and as extremely impressive.
- In C. S. Lewis's The Last Battle, the dwarves' rallying cry is "Dwarves for the dwarves!" They don't want the Aslan side or the Tash side to win. During the battle they use their arrows to help whichever side is losing at that particular moment.
- From Starship Troopers: "Either we spread and wipe out the Bugs, or they spread and wipe us out - because both races are tough and smart and want the same real estate."
- Averted in Max Fraj's Labyrinths of Echo. Understandable since most humanoid species there are cross-fertile.
- In Sergey Luk'yanenko's "Key Dach" novels, as those take place in a modified Master of Orion universe.
- In V. Panov's Secret City, partially enforced by The Masquerade of the setting when dealing with respective Muggles, with notable differences among the magical nations and among the magical species making those up.
- In V. Zykov's Way Home: both examples (reptarkhs, reprokhorses, light elves, dark elves, high and common dragons) and counterexamples (humans, dwarves, goblins).
- In most works of V. Ivashchenko: united elves, fractioned humans and tribal orcs.
- In Andre Norton's Secret of the Lost Race, an alien race can interbreed with humanity -- and in fact must to reproduce -- and this is greeted with revulsion and accusations of disloyalty by many humans.
- In Poul Anderson's "A World Called Maanerek", Sonna thinks it a glorious thing to make all men brothers again. It is when she learns of the Dystopian nature of the Hegemony that she rejects it.
- In Warhammer 40,000, the official priciple of the Imperium is xenophobic species loyalty.
- Pervades the Chrono Trigger / Chrono Cross universe, with humans, mystics, demihumans, dwarves, and fairies each only looking out for their own.
- Inhuman - Myches have this as a borderline hat, after the whole species spending a long time in slavery.
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