I begin with deception in the way that I act
Then grow in obsession with only the facts.
I sometimes yell loudly and sometimes I whisper
Some things may confound me but don't let me wither
For if I'm neglected in present or past
Your life is affected and peace may not last
What am I?
My first two lines are wordplay. The rest of the lines validate what I am by my characteristics.
In addition to the word play lines:
I'm an artist and a fake: this is true as my first
Then I ask bio or physics: which one's the worst?