The Milky Way
Humanity had problems. First, we came up with technologies - to defeat them, we hoped. But the people making the problems were the same ones making the technologies, and we only made it possible to hurt eachother faster, easier, and cheaper than ever before. Then we ran from our problems, out into the vast expanse of space, and we swear it would've worked if only we were better. End result - we brought our problems with us, and met other people with the same ones. The galaxy is the same size it's ever been, has the same things in it - we're just in more of it now.
Maybe the galaxy is a house of cards, and everyone in power is poised to flick out the foundations. Maybe the galaxy is a pie, and we fight for crumbs whilst the powerful squabble over the biggest piece. Maybe it's a time bomb, or a snakepit, or a Colosseum. But before all that, reluctantly, it's home.
Home to whom? The United Galactic Commonwealth, for one - Earth's world government, that turned into a solar government, an interstellar government, and now pushes at its borders, swelling like a gorged pig or a pustule. When it called itself "Galactic", it didn't count on meeting other people. Recently one set of territories has seceded to form the Free Peoples' Republic of Carina, bringing together colonists, indigenous species, and robotic slaves in an uprising against their masters that led to civil war. It has been in stalemate for five years now, with no signs of letting up.
Further to galactic north, the Conglomerated Pyrani Holdings are almost in ruin - once owning half the galaxy, wars with the Dominion and the Commonwealth have robbed them of most of their territory, splitting them down into warring corporations running private planets like fiefdoms. But that territory, largely, was never theirs - the Great Scutoid Dominion now occupy almost all of what they consider their ancestral lands, and hold their borders tight against infiltrators from outside and defectors from within.
At the galactic core, the Covenant of Vitria forge scientific and technological paths incomprehensible to the rest of the galaxy, all in devotion to equally incomprehensible gods. And on the New Outer Arm, just beyond the edge of Commonwealth space, colonising ships come back either not at all, or horribly, frighteningly different - which would make more sense if anybody actually lived there. Amidst it all, the de facto galactic capital Alicante stands, a free system bordered by factions who all have their designs on it. There, at least, anybody can exist in harmony with anyone else - as long as it stays standing, that is.
This fine mess is where you find yourselves, and eachother.