It would be to advantage if the reader was aware of Cain.

There are many stories of Cain. All the legends agree that he was the first son of Adam and Eve. He killed his brother Abel, a shepherd, due to jealousy, and was marked by God.

The linage of Cain was short. with Lamech being the most prominent member He had two wives and two children by each wife. Here, the mystery of Cain begins and technically ends. It is the last time Cain or any of his line are mentioned (in the bible).
Adam and Eve had a third son, Seth. This is important for two reasons—Seth is the founder of the human race; and secondly, this is the first mention of natural death in the bible. From this point on, the bible lists the number of years a person had lived.

Cain and his descendants are never recorded to have died. This leaves the reader to trust they are still alive; especially Cain. For God said whoever killed Cain would suffer his wrath—and Death is but an angel. People are dieing all the time, illustrating how the Death angel is still at work. It is safe to infer that Death never took Cain, or God’s wrath would of manifested into the extortion of the Death angel.

In the book of Genesis (Chap. 4), it is leaned that Cain takes a wife and builds a City. This City is named Enoch, after his son.

Although the Book of Enoch is considered as apocryphal, but it was clearly known to early Christian writers as the following quote from 1 Enoch 1:9 indicates:
"In the seventh (generation) from Adam, Enoch also prophesied these things, saying: 'Behold, the Lord came with his holy myriads, to execute judgment on all, and to convict all the ungodly of all their ungodly deeds which they have committed in such an ungodly way, and of all the harsh things which ungodly sinners spoke against him'." Jude 14-15

The "Book of Enoch", translated by Richard Laurence in 1821 from scrolls found hidden in caves in Ethiopia in 1773. These scrolls were evidently hidden in the same historical period as the Dead Sea Scrolls.

The Book of Enoch was not included in either the Hebrew or most Christian biblical canons, but could have been considered a sacred text by the sectarians. The original Aramaic version was lost until the Dead Sea fragments were discovered." "The original language of most of this work was, in all likelihood, Aramaic (an early Semitic language). Although the original version was lost in antiquity, portions of a Greek translation were discovered in Egypt and quotations were known from the Church Fathers. The discovery of the texts from Qumran Cave 4 has finally provided parts of the Aramaic original.
The "Book of Enoch", like the Book of Seth, and other ancient manuscripts, was denied entrance into the "approved" version of the original Bible by the Nicene Council of 325 A.D.

Click Here to Open the Book of Enoch

This Book contains:
Chapters I-XXXVI
XXXVII-LXXI (The Parables)
LXXII-LXXXII (The Book of Heavenly Luminaries)
LXXIII-XC (The Dream-Visions)
XCI-CIV (A Book of Exhortation and Promised Blessing for the Righteous and of
Malediction and Woe for the Sinners).

Assyrian and Akkadian Demonology

Iranian Demonology

Jewish Demonology

Early Christian Demonology

Medieval to Modern Demonology

The Book of Enoch

The Nephilim