The Holy queen that is the upper Shechinah, Binah, and the aspect of the good inclination come down on Shabbat. She is included from Ten Sefirot and decorated by seven holy names. She comes with camps of angels to meet the King that welcome her with more camps of angels.
The evil side is like a maidservant that is the aspect of the evil inclination. She stays in the dark, like a widow without a husband or support of angels.
There are those who worship the darkness and connect to the evil side on Friday and Tuesday nights. These nights are easy to connect to the dark maidservant with negative feelings. These actions create affinity with the negative side.
The special lights of the soul at the levels of Nefesh, Ruach and Neshamah from Shabbat leave us on Tuesday night and the dark side can easily get to us.
God created a parallel system of Good and Evil. We can easily avoid the negative side/inclination when connecting to the light of Shabbat with joy and singing. Without proper connection to Shabbat we would fall to the negative and dark side.
We should avoid walking alone on Friday nights because the ‘maidservant’ is alone and can easily get us.