Cavity
He will always remember the feeling- or non-feeling- of her hugging him, tightly around the waist- as high as she could reach on him, back when he was in the armour. He couldn't feel her arms holding him; the smooth warmth of her skin pressed against the cold, unfeeling, senseless metal of his body; the soft flowing masses of her hair between his fingers when he hugged her back; her long slender hands held in his own huge blunt gauntlets; the light, hot rushes of air as she whispered breathily into the space where his ears once were. What he could feel, however- what he is unable to forget and still feels even now- is the much more real sensation of tingling, breathless heat, which spreads through the empty cavity of his chest whenever they touch.