Bibliotecapleyades: Divine creatures from the Old Testament, associated with the Cherubim, and later taken to be angels. The root of Seraphim comes either from the Hebrew verb saraph (’to burn’) or the Hebrew noun saraph (a fiery, flying serpent). Because the term appears several times with reference to the serpents encountered in the wilderness (Num. 21.8, Deut. 8.15; Isa. 14.29; 30.6), it has often been understood to refer to "fiery serpents." From this it has also often been proposed that the seraphim were serpentine in form and in some sense "fiery" creatures or associated with fire."
Note: In ancient times many of the gods were called the "Shining Ones." The word Lucifer means Shining One. If Serpentine angels fell and mated with women in Genesis 6 and had children, obviously the physical offspring would be reptilian by nature.