I have been caught by this damnable ship and now my brain has made it my and everyone else's problem. So... who wants to dump them into 40k?!
In the many millennia before Big E Genocided Crusaded across the galaxy, the Eridians had long since expanded beyond their system and have altered their own genome to be more compatible across various atmospheres and thermal ranges -yes, that means that Rocky can hug Grace now-.
Sight is still beyond them, so they compensate with cybernetics. By the time the Iron War transpired, and Big E did his thing, the Eridians have been limited to regions on the edges and past the Light of the Astronomicon, staying around Sagmentum Pacificus where the Imperium's influence is very limited and conflicts only happen under very calculated and specific circumstances, such as the one that got them Gratias.
Eridians do not leave their own to the tender mercies of the Imperium if they can help it, and if they can nab anything of value alongside that?
Heretek Magos Genetor Rylahan Gratias.
One learns very quickly why calling an Archmagos an "Utter waste of holy cybernetics!", is a terrible idea. Especially when you are right about your innovations in an institution that abhors such notions. His boss, Archmagos Stratt, would save him from his punishment, even though he'd wish she hadn't. Especially not in the way she did, even if he understood why in the end.
He got an alien BFF out of it. He would rather not have the night terrors, the memory problems, or tearing up whenever he sees a servitor though.
Symon the Pelager and Prophet of the Pinhole God
You never know what kind of shit one might get into when they are raised in a cult. Especially when you are part of a weaponized breedstock of humanity made to fight the incongruent battle automata of the Men of Iron. Symon was their hound, sent to do the dirty business no one else, but his kindred, could and he was good at it. Sadly, he only learnt of the true nature of the cult he was raised in too late and when they no longer had any need for him, he was left abandoned and at the tender mercies of the Imperium.
But an unscrupulous Inquisitor is rarely keen on wasting suck potential.
But when a failed mission, a prayer, a brush with an alien divinity and a simple desire to live intercept things rarely ever go the right way.
Well, at least he's not stuck in a space hulk anymore.
Would do without the nightmares, the alien divinity's voice in his head echoing his every insecurity and sin. At least it becomes quiet when this guy that is friends with aliens, of all things, talks to him.