After the fall of the Roman Empire in 476 A.D. a time of chaos began known as Dark Ages in Europe. The last Emperor of Rome, Romulus Augustus, was defeated by the German Goth Odoacer, he however did not die but escaped to Britain.
In Britain; the wizard Merlin helped King Arthur to establish the kingdom of Camelot, and mentored the Black Knight (Sir Percy of Scandia) to oppose the evil influence of Arthur's illegitimate son, the knight Mordred. In the end, Mordred and Morgan le Fay brought down Camelot, but were killed themselves in the process. (All of these people would later manifest, in various ways, in the present.)
Iron Man and Doctor Doom were present at that time, following a battle and the treason of an employee of Doom. Iron Man allied himself with Arthur, and Doom with Morgan, but the two time travelers were eventually forced to work together to return to the present.
At some point prior to the fall of Camelot, Modred the Mystic (no relation to Mordred) was approached by Merlin (or an impostor) to study magic in Camelot. Modred was instead corrupted by the power of the Darkhold, and would lose his soul and his love but would gain near-immortality and a mastery of magic. He would battle Chthon and the Darkholders through the modern day, but would bear a deadly vendetta against Merlin and his allies.
Merlyn wanted to Tommy Tyme a lesson about magic, the wizard tripped the boy, activating his Clock of the Ages and sending him back in time to England in the 6th century. There Tommy assisted Merlin in rescuing the captured King Arthur from the evil Black Knight. When Tommy returned to his own time he had learned a greater appreciation and belief in magic.
Big Mother and her son, Grendel, once terrorized the marshlands surrounding Heorot Hall in Scandinavia in the 6th century AD. Beowolf came to the aid of the Danish King Hrothgar, whose hall was raided each night by the hideous man-eating monster Grendel. Beowulf slayed Grendel, then Grendel's angry mother, and ruled as king of the Geats until he himself was slain in battle with a dragon.