It's only a trick of the light, an illusion. It never seems to move after all, but only watches--silently, patiently, steadily watches you.
But you, you are curious, so you test it with a stick between the bars.
And nothing happens. Nothing seems to be there. Only a trick of the light.
And yet it persists in watching you.
You are dissatisfied with the stick test. Foolishly, you want to feel it for yourself. So you push just the tip of your little finger through the grate. After all, you could afford to lose just one little tip.
And nothing happens.
And still it waits, staring calmly as a cat, feigning disinterest.
Emboldened now, you tempt it, pushing further in, putting all four fingers into the slotted mouth. It is wide enough. You wiggle them like bait, proving to your cowardly companion that there is nothing there. It's just an illusion, nothing dangerous.
You both have a good laugh, a relieved and embarrassed laugh. And then you begin--from the furthest reach of your folly--to pull back, attempting to reclaim those appendages that now are good as gone.
For it has played this bloody game before. One alone suffices as both a handle and a straw, but when it is sure that you will offer it no more fresh meat, when it is confident that waiting longer will not gain it the bones and marrow of other hand, only then…
...does something happen.