Sounds like you either have a bull in your house or you've been shot? I just have a brief report to share

At night, when the silence draws near, I summon your shadows to leer. I dwell in your chest, Denying you rest. I’m the whisper that none wants to hear.

I live on your desk. Straight, black. Keep things together. Watch out for my bite.

I stand in your way or build what you need, A barrier or base, depending on deed. Kids stack me up high, then laugh as I fall, Or use me to build sturdy forts or a wall. When I visit writers, I tangle their words, Yet lay the foundations of cities and curbs.

In glass and mercury I lie, a slender line, I climb, descend, in Fahrenheit or Celsius I define.