The thing's first goal is readily achieved as it forces Cassi to the ground.  But her space suit seems reluctant to provide it anywhere to inject her.  The creature is forced to paw at her back until its actions finally pull her tight top out from under her waistband.  With that obstacle removed, her skin is easily displayed and its claws are able to do their work.  She feels them dig into her skin, not even enough to draw blood.  But enough to do their job.  Slowly her struggles calm to a mere shadow of what they had been.  She never gives up though.  Not even as she struggles to keep her mind from drifting.  She continues to fight with all she'd got... it just slowly becomes less and less.