Good and Evil

I stand beside my double,
And look into her face.
I cannot see her eyes,
But she's looking right at me.

We are the exact same,
Both pretty, young and thin,
But when I look at her,
I do not see myself.

My sister, my friend, my twin.
We are forever bound,
Never to be distant,
We're always hand-in-hand.

I am a sweet, light taste,
You are a bitter slap.
No one ever listens to you,
I am the one in charge.

I am the louder one,
People always pick me,
I am always in their hearts,
You are good and I am evil,
Why can't you be as loud?