Black Line

I'm the silver lining,
No I'm a black line,
I cause the flaws,
Call me a flat line,

You say I'm benign,
No I am cancerous,
I limit living time,
Never a man of bliss,

I'm a human of peace,
Never do wrong things,
Opposite of a beast,
Actually I am wrong,
An infection like yeast,

I should win an award,
The Nobel Peace Prize,
At an unanimous accord,
No I'm actually despised,
Talked about and ignored,

Black line to the silver line,
The dullness to the shine,
The dumb to the smart,
And the mean to the kind...