Answer:
They're up near the sky, on something very tall. Sometimes they die, only then do they fall.
In your fire you hear me scream, creaking and whining, yet I am dead before you lay me in your hearth.
As destructive as life, As healing as death; An institutioner of strife, Just as prone to bless. It is all that is good, Yet with an evil trend; As it was the beginning of things, It can also be the end.
I'm not man's best friend, I'm their enemy, I can mark your end, yet you do not see me, I am very small, but very tough, If you have me, then you have it rough.
You use it between your head and your toes, the more it works the thinner it grows.
If itβs information you seek, come and see me. If itβs pairs of letters you need, I have consecutively three. What am I?