Where the Monster Lurks

The entire time I was writing this I was describing a vent, it turned into a story

Bottomless hole,

Between the jail bars,

Covering the horizontal doors,

Protecting us from the creature,
That lurks beneath our feet.

When the creature gets upset,

Hot steam rises,

Heating our blood,

When lonely,

Cold air appears,

Covering our bodies with shivers.

The monster always lurks below us,

But...

Is this keeping the monster caged in,

Or keeping us locked out?