1.  They started out in the 1960’s as the hosts of two DC Comics horror anthology titles, House of Mystery (Cain) and House of Secrets (Abel).  They also appeared in other DC horror titles, such as Plop! and Secrets of Haunted House. 

2.  Cain’s physical appearance was original modeled on Len Wein, a noted writer of comic books who was just getting started at the time.  (Tres chic goatee, Len!)

3.  Mark Hanerfeld, who worked at DC and was involved in Abel’s creation, served as Abel’s initial physical inspiration.

Cain

4.  Cain’s fashion sense is lamentably very much of its period; he typically wears a very polyester-looking back-belted brown leisure suit with bell bottoms.  (If I have just described an item in your current wardrobe, please know that I’m sure there are plenty of items in my fashion sense-free wardrobe that would cause you equal amounts of amusement.)

5.  The characters became more fully developed when Neil Gaiman drafted them as part of “the dreaming,” the realm of the Sandman, in his landmark Sandman series, where they are the personification of the characters in the Biblical story – and so Cain is constantly killing his brother Abel.  (He never does stay dead.  Much like my Uncle Mike, but that’s another story.)

6.  Cain has been described as sounding like Vincent Price, a charge which annoys him.  (You don’t want to annoy Cain.  Just ask Abel.)

7.  Even though he is the guardian of the House of Secrets, Abel has a hard time keeping a secret.  Which annoys Cain.  (See above about annoying Cain.)

Abel

8.  Abel wanted to call his new baby gargoyle Irving, but Cain rather forcefully made clear his view that all gargoyle names must begin with a “g.”  After he returned from the dead, Abel acquiesced.

9.  Before getting picked up for Sandman, Cain (and to a lesser extent Abel) made some appearances in DC’s Blue Devil comic.  Very odd fit indeed.

10.  Cain gets chosen by the Sandman to be an envoy to Lucifer because he bears the mark of Cain; any other envoy, unprotected by such a mark, would have been tortured (and most likely destroyed) by Lucifer.  (Do Not invite him to your next party.  Lucifer, that is.  Or Cain, come to think of it.)