Before I say anything I just want to say that this actually came to me in a dream so it might seem (and probably is) a bit crazy.
Introducing the Infiltrator strain, something entirely different from what we’ve seen so far. Losing their entire ability set (cloak, pounce, and crippling strike), the Infiltrator gains a far more insidious ability, the ability to morph their exoskeleton to resemble that of a human of choice, at a glance this sounds rather overpowered but let me ramble a bit here.
Stats: Health 450 (unchanged), Plasma 150 (-250 from base value), Plasma Regen 1 (-3.5 from base), any other stats un-mentioned here are unchanged.
Starting off their new moveset with their first and primary ability “Morph Exoskeleton”, targeting a living or dead human with this ability will begin the process of assuming their form, upon completion the Infiltrator will visually be identical to their target, using this ability on yourself reverts your form (this should be very noisy, bones crunching and the likes), or re-assumes your previous disguise if you are currently in your natural form, this does not come without downsides and a couple benefits. Starting with the maluses gained while morphed, the first and arguably largest is losing your ability to speak both normally and in the hivemind (you can still emote though), second all damage you take is doubled this means your effective health while morphed is marginally less than that of a runner, and finally all attempts to attack will deal minimal damage about as much as a normal punch from a human. On to their boons while morphed, a key ability gained while morphed is the ability to “scrounge” access from deceased marines enabling mobility through normally restricted areas, secondly while morphed ARES cannot detect this strain aboard the Almayer delaying detection and response from the crew.
Continuing my explanation of how morphing would work, the disguise is not infallible attempting to use a health analyzer on a morphed Infiltrator will reveal that they are not what they appear to be, additionally attempting to strip an Infiltrator will also reveal their false nature, and finally attempts to restrain a morphed Infiltrator with handcuffs and other such devices will fail breaking the Infiltrator’s cover.
Secondly Infiltrators gain a weak corrosive acid ability costing 150 plasma and being usable while morphed this allows for occasional sabotage of strategic assets if left unresolved.
Third comes “Choke Slam” after a moderate windup accompanied with the same sounds as un-morphing shed your disguise and rush forward slamming the first human collided with to the floor stunning them briefly.
Fourth and final is “Headbite” mostly borrowed from the Vampire strain albeit slightly different in functionality, rather than outright healing you this headbite enables regeneration off of weeds, this is to encourage hit and run tactics rather than slugging out bigger fights.
Overall I think this strain would add a degree of paranoia to the otherwise mundane shipside roles (outside of hijack at least), and also give something more for MPs to do once the marines have deployed.