Black in disguise, a piece of my soul

I never have to struggle, it is under my control

Same body structure as mine, but won't be developed in real

Expressionless still has effects, a portion of us being ideal

Visible to others only when it wants

In case there is light, it gets a chance to stand off

This follows me at day, never leaves me even at night

That wakes up with me, as well as sleeps with me inside

It's like my dark soul keeps hiding beside

The darkest part, I will never show anyone in my life.

It carries anger and delight, yes it is alive

It never reacts nor fights

Just keeps watching and stores all my darkest sides.