one by one the specimins in your laboratory dissapear completely, the glass of their aquariums & terrariums unbroken. the night you keep up watch in the lab is presumably the night that the xenomorph devours all the blood reserves in the medical bay. slowly the vessel is left empty, devoid of any organic tissue exept you & presumably it. your prayer mat, synthesized from hydrocarbons, is the last thing to go, leaving your knees on the bulkheads. the moniters show the hull as pristine, unpockmarked by the expected impacts of micrometeorites.
in your mind, the thing has grown, has become some great shaitan. you've ascribed methods to it, an agenda, as supernatural aspect. it was fate that brought it to your ship, leaving the ribcage of support struts gaping around the now cathedral like emptiness of the main berth. your security system was flawless, without equal. a single weapons group (of which there are many, mounted both inside & out) is capable of turning enemies into vapor, of boiling off planetary atmospheres. you value your hermitage; you even went so far as to cripple the ship's artificial intellegence. it went from super-genius to mongoloid infant with the flick of a few switches.
but here you are at last, invaded.