Well friend I don't find anything in the word of God that says where demons came from. Jesus is the only person in the Word of God who used the term " Blasphemy of the Holy Spirit" and it was in context to say the work of God was done by a devil.
Look even in the end the old dragon will use the same trick, he'll give his great power, which is the power of the Lies, to the man of sin and the idol of the beast. There are three of them. They are the spirit of devils. That's the demons.
Revelation 16:13-14
13 And I saw three unclean spirits like frogs come out of the mouth of the dragon, and out of the mouth of the beast, and out of the mouth of the false prophet.
14 For they are the spirits of devils, working miracles, which go forth unto the kings of the earth and of the whole world, to gather them to the battle of that great day of God Almighty.