Science Fiction Book: två främmande fraktioner kämpar, så småningom blir människor involverade [duplicera]

Mitt förslag är Den fördömda trilogin av Alan Dean Foster .

Du har två stridande fraktioner:

Two major alien civilizations, the Amplitur (a squid-like species with telepathic and mind-controlling abilities - which they couch as "suggestions") and The Weave (a confederacy of more or less equal species), have been fighting a war for several millennia. The Amplitur are attempting to join all sentient species in what they call the "Purpose", an alliance which they "guide" to some unknown (even to them) end. The Weave is a group of species allied in opposition to the Purpose.

Den fraktion som slutligen hamnar med mänskligheten, tycker inte om krig:

...most sentient species in the galaxy have evolved to be incapable of committing violence against other sentients (violence of any sort being most un-civilized, but against another sentient being a [literally] unthinkable crime)...

De tycker att Människor är ganska bra på det hela slaget:

On a mission to find new resources and allies, a Weave scout ship discovers Earth circa late 20th/early 21st century AD and finds that humans are uniquely suited as allies, in that they have the ability to fight. They are adaptable to a wide variety of environments, have few (or sometimes no) compunctions regarding war (humans having been fighting each other for all of their recorded history), and above all seem even more enthusiastic when their aggression is focused on non-humans. Eventually Weave xenopsychologists determine that Earth's fragmented continents resulted in a species that evolved to fight, compete, and kill for dominance. They surmise that all humans are born hunters and killers, but that intelligence is starting to drive them toward the abhorrence of violence that other "civilized" species consider normal.

Minst ett tecken är oroad över att mänskligheten kan vara problem senare:

During the course of her research she comes to the conclusion that unless Humans can be 'civilized' somehow they will eventually turn on the rest of the Weave races once the war is over.

Och det publicerades i början av 90-talet! Så, förhoppningsvis är det här du letar efter! Hur som helst, lycka till!

En möjlighet är Död eller ära -serien av Vladimir Vasilyev. Från Wikipedia-artikeln:

The novel is the first of four describing the future of humankind among the stars. Humans have acquired faster-than-light travel centuries ago (it's only recently at the galactic scale), but does not progress further. All energetic and ambitious people have moved to new colonies, leaving the Earth to stagnate.

The galaxy is ruled for long by an alliance of five powerful races, mired in an ancient war with extra-galactic Imperishable. Without this war, the Alliance would enslave the Humankind like it treats other newcomers, but now Svaighs just don't have the will and resources. Despite this, most people live in filth and poverty. But the situation changes, when people gain a bleak chance to succeed — and show the Galaxy they aren't going to refuse of it, these Homo with a motto Death or Glory.

Det passar in i att det i grunden finns två olika fraktioner, och människor var inte ursprungligen en del av kriget. Däremot tycks deras skicklighet till stor del bero på att de är perfekt dimensionerade för att använda Departed Ones-teknik, vilket är överlägsen den existerande Alliance tech. Det verkar som att den primära källan till konflikt är faktiskt den inre mänskliga maktkampen, eftersom skeppet väljer ledare baserat på den första människans personlighet för att upptäcka det, vilket inte stämmer överens med mänsklig regering.

Det finns tre fler böcker i serien, Black Relay , Legacy of Giants och Ingen men oss , vars detaljer är du hittar i Wikipedia-artikeln.