As I was going over Black Adam’s backstory, and I noticed an interesting addition but in through the New 52, and in specific, Adam’s nephew, Amon.

Now, in New 52 spoilers:
Amon was the actual champion selected by the wizard, not Adam. Amon just shared his powers with his uncle, and Adam murdered him to keep them.
end of spoilers

It dawned on me that Amon has quite a few traits in common, both in appearance and actions (albeit more post Crisis Billy than New 52, but I think there’s still enough similar). Considering Adam does believe in reincarnation (as he believes Adrianna Tomaz to be the reincarnation of Isis), I would find it an interesting take if Adam believed Billy is a reincarnation of the nephew spoilers:
he murdered so long ago.
end of spoilers