Because even though he's dead, Yami Yuugi is still human.

Lost
By Tyger.

I wander the halls of my soul at night, when my Aibou is asleep. When my mind is the most awake, fuelled by the darkness of the night.
Like Shaadi, I search for the true room of my soul. I haven't found it yet.
The deserted corridors of my mind are eerie at night, when Aibou's cheerful soul is not awake to brighten up the world. It scares me.
I'm alone in my own mind and it scares me.
I'm lost.
I'm lost and I'm scared.
I end up curled in a corner.
Waiting for my saviour to find me.