The four thousand-year time skip makes me wary- I read too many bad stories that use such time skips to justify extreme changes in their characters and setting. Hopefully, you won't repeat the bad writers' mistakes. (Glares at Gene Roddenberry for reducing the Federation and its Starfleet into spineless pansies who think SELF-DEFENSE is an act of aggression, J. J. Abrams and Rian Johnson for reducing the New Republic and its Jedi into suicidal fools who'd rather let the galaxy burn than lift one finger to save it.)This is confusing. You should specify Rik Oxymin and Earlin Xurfanous are from different Mechanicus factions, and identify these factions.
The investigation into Rik Oxymin’s disappearance led the Mechanicus to believe he had been murdered by Earlin Xurfanous or another agent of the Mechanicus.
No no no. The fleet has been in the future for about a couple months, best. The future is the Forty-Seventh Millennium. Its been a couple of months for the fleet since the fall of Cadia.
They are not from different Mechanicus factions. There is only one Mechanicus here.