Answer:
My life can be measured in hours, I serve by being devoured. Thin, I am quick. Fat, I am slow. Wind is my foe.
When I live I cry, If you don't kill me I'll die.
I am seen in the water. If seen in the sky, I am in the rainbow, a jay's feather, and lapis lazuli.
A hole leading in, a hole leading out, we connect to a cavern that is slimy all throughout. What are we?
I can be written, I can be spoken, I can be exposed, I can be broken.
I am your mother's brother's only brother in law. Who am I?