The first fear is God his former father who created him and later sent him to Hell. The second fear is to Jesus Christ he had no power over him in the desert no temptation at all.
The third? Satan's demons in Hell who do what they are told. In his own dark mind Satan must wonder if one of his demons betrayed him to take over.
Not just earth history where some wanted power and betrayed others for selfishness. Satan caused a rebellion and wanted to sit on God's thrown.
Demons in Hell would want to take over if they could it does make some people think more so Satan to get betrayed by his own kind.
