So, I've been thinking and I've some new connections to many different characters that mostly spin some old Arthurian legends and, well, comic books. Some of this is inspired by Jack Kirby, a comic book artist and editor.
My theories began with similarities between Bob and Etrigan the Demon (he was one of Jack Kirby's DC Comics creations). Etrigan was the son of the demon Belial, and half-brother to Merlin. He has orange skin (the same colour as Bob's eyes), horns, and ears shaped like bat wings.
Merlin summoned Etrigan to gain his secrets and unable to do so, bound him to Jason Blood, a knight in King Arthur's court. This rendered Jason immortal (similarities to Harry) and he often thought of it as penance or a curse. After the Fall of Camelot Jason Blood and Madame Xanadu (those of you that read Thomas Malory's Le Morte d'Arthur, she is identified as Nimue, youngest sister of Morgana/Morgaine Le Fay) keep traveling England for an unspecified time, assembling a rag-tag team of Dark Ages based heroes and villains, like Vandal Savage (solid ties to Marcone), the female Shining Knight and the warrior woman Exoristos (The Exile in Greek -- solid ties to Karrin Murphy) to fight Mordru and the Questing Queen (connections to Cowl). As eventually they parted way, Jason Blood resurfaces in recent times, becoming a prominent demonologist in Gotham City.
Etrigan is a demon from Hell who, despite his violent tendencies, usually finds himself allied to the forces of good, mainly because of the alliance between the heroic characters of the DC Universe and Jason Blood, a human to whom Etrigan is bound. Etrigan is followed by the long-lived Morgaine le Fey, who lusts for Merlin's secrets. That leads to Etrigan's first major battle. Over the years, Etrigan both clashes with and occasionally aids Earth's heroes, guided by his own whims and Jason's attempts to turn his infernal power to good use.
Remarkable what comic books can inadvertently shed light on.