Ok. I have had an idea. Still outlining it, but I can see the general shape of it.
Hmm. Where do I start?
The year is 12,347 HE (Just 2347 CE, but with the Human Calendar date) and humanity has perfected the Alcubierre Drive. We have colonized Alpha Centauri, Barnard’s Star, Wolf 359, Lalande 21185, and Sirius. Humanity is known as the Terran Commonwealth, and is a militaristic democracy. At the start, Humanity is unaware of any other galactic civilizations. The first contact comes as a Coalition incursion and raid on a convoy. The Dominion approaches Humanity, presenting themselves as trustworthy allies and offering support. We accept.
OH, STORMS, I FORGOT TO TALK ABOUT THE DOMINION AND COALITION!
The Coalition of Free Species and the Dominion of the Galaxy are the two alien alliances. The Dominion of United Civilizations (or just the Dominion) is an alliance of five species (led by one of them) that want to rule the galaxy. They present themselves as nice people who want to bring order, but they are actually manipulative and ruthless, willing to subjugate or destroy any species that resists them. They want to 'protect' Humanity from the Coalition of Free Species (or just the Coalition), which is a group of three species who are trying to resist the Domnion. They use guerrilla attacks (which humanity tends to see as terroristic, so Humanity dislikes them). The Coalition's worlds are being taken very quickly, and they're relying on more secret colonies.
It's only after a Terran destroyer captures a Coalition raiding vessel and interrogates the crew that Humanity begins to realize the true nature of the Dominion. Y'all can probably see some Star Wars inspiration and other stuff, as well.
Oh, and yes. I will make it as scientifically accurate as I can without help from an astrophysicist.
Now, time to write.
I'll keep y'all updated.