What Am I Riddles

Question: I am a thing, when I look at him , he looks at us!! who am I???

Question: I'm small but big, i hide behind you but come out when you fall... What am I?

Question: I always murmur but never talk, i always run but never walk, and I have a bed but I don't sleep. What am I?

Question: I don't like crackers and I don't drink tea. I just want to eat what I used to be.

Question: When I come in, someone else leaves, I know everyone, yet no one knows me. I'll meet you all only once in your life, Causing mayhem and mischief and sorrowful strife. What am I?