Fireteam star

I haven't thought too much about the plot to go with this idea.

In Star Wars with an aliens fireteam elite system.

Example

As he woke up he received memories, not his own. Apparently he was a new member of the colonial marine's, a military group who's main task was the eradication and containment of an parasitical alien life form, nicknamed Xenomophs.

Supposedly for over 1000 years the marines have kept this scourge away from the galaxy, in this small sector in the unknown regions away from the politics and corruption of the galactic senate.

They keep themselves secret from the republic, in fact the only extended time spent in the republic is for recruitment, and even that is done in secrecy.

The marine corps mostly recruits those whom are having a tough time, in debt, have minor crimes for good reason's; like a father stealing food for his children, those whom are idealistic and want to make the galaxy a safer place etc.

The corps has its own planet in the unknown region where it relocates family from the galaxy, where food is grown, factories and shipyards are and military training facilities. The only thing the really buy from the republic is bacta and some times tibana gas for the few blasters in use.

The marines after centuries of fighting Xenomophs found that 'sluggers' ,as they are known here, are far more effective against the hordes of enemies they have to face. A blaster might kill a Xenomoph but a bullet will go through one and hit another.

Due to the need for secrecy we have never had the numbers to eradicate the bugs, they have infested over 50 large and small planets, so we contain them by making sure no ship from the outside comes to the planets and by a crude form of population control, we really just kill as many as we can.

The need for secrecy is very simple, the sith. Ironically the once whom started our little group was a failed sith acolyte, failed because he fell in love, and with his unique perspective he knew that the sith could never find these creatures or the galaxy may never survive.

Also scientists, they go nuts around xenos, it has been discovered that the Xenomophs have a corrupting presence in the force, very small and subtle, what happens is the scientist eventually is seduced by how "perfect" a creature they are, how beautiful and deadly they are. Ironic to their hideous and frightening appearance they produce and aura like a succubus.

The reason we say scientist's and not others is because most of the time they are the only ones around xenos long enough to be affected by the corruptive aura. With this discovery we have over the millennia found ways to study them safely, put them on a force cancelling cell etc.

Example over

That's all I could think of for a plot of how the colonial marines exist and why no one knows of them, also why they haven't exterminated them yet despite the large population of the galaxy.