While Xanatos was still in prison, he arranged for a Steel Clan robot to attack Goliath and wound him, afterwards having Owen obtain some drops of the gargoyle’s blood under the guise of treating his injuries. Sevarius used the blood to create Thailog, artificially aging him to the same biological age as Goliath in a matter of months; he also tutored him through subliminal methods, indoctrinating him in Xanatos’s ethical code of utter amoral pragmatism.
Xanatos and Sevarius succeeded too well in this; Thailog decided to go into business for himself, and duped Sevarius into "kidnapping" him and holding him for a twenty million dollar ransom. When Xanatos came to pay the ransom, Thailog ambushed both him and Sevarius, seized the money for himself, and planned to kill them both by locking them up within an abandoned oil rig off Black Rock Point and setting the barrels of oil there on fire. Aware of his origins, he arranged for his third "father", Goliath, to join him there, originally considering (with a bit of an effort on his part) to share the money with him. But when Goliath initially regarded him as an abomination and made that clear in no uncertain terms, Thailog decided to kill him as well. Elisa rescued all three of Thailog’s "fathers" from death, but Thailog escaped with the money.
He went to Paris, where, not long afterwards, he met Demona. Deciding to make use of her for his own ends (and probably physically attracted to her in the bargain), he became her mate, and they decided to pool their resources, forming Nightstone Unlimited. They also decided to add to their wealth through Demona wedding Macbeth as Dominique Destine, then afterwards locking him up and making him appear to be dead so that she could inherit his wealth; Thailog, however, plotted to turn this to his own advantage again by tricking Demona and Macbeth into killing each other so that he could inherit all their wealth. Elisa managed to foil this scheme when she and her companions arrived in Paris during the Avalon World Tour, but Thailog and Demona fled Paris together, Demona still none the wiser about her mate’s betrayal of her.
They later on returned to New York, where they arranged for Demona to be captured by the clan so that she could first arrange to have the gargoyles cloned, supplying herself and Thailog with followers, and then escape, leading Goliath’s clan into a trap. Thailog directed Sevarius in the creating of the clones of Hudson and the trio, but had him secretly create a fifth clone, Delilah, whom Thailog intended for his new mate (he had already decided to dispose of Demona, whom he considered too much of a loose cannon). The scheme proceeded according to plan, until Thailog, having captured the clan, ordered Angela’s death; Demona protested this, and after learning about Delilah, furiously turned on him. The two wound up fighting each other in the middle of a burning roller-coaster at Coney Island, where Thailog appeared to perish. However, he survived, and is plotting fresh schemes against Goliath and his clan. Thailog would have also gone on to become their primary antagonist.
Thailog currently goes by the alias of "Alexander Thailog", a reclusive financier whom nobody has ever seen.
Physically, Thailog bears a striking resemblance to Goliath, although with altered coloring because of his artifically-accelerated aging. As a result, his hair is white, his eyes are red, and his skin a deep violet. He wears high-tech battle armor, which he obtained after his escape from Black Rock Point.
Thailog is one of the most thoroughly malevolent of the Manhattan clan’s adversaries. He even seems to be aware that he is evil - and is proud of it. Thoroughly cunning and duplicitious, he will happily betray anybody for his own benefit, and is ever ready to enrich himself at others’ expense. He also seems to have something of an Oedipus complex, both in his attempts to kill his "fathers", especially Goliath, and in his choice for mates (first Demona, who was Goliath’s past mate, and then Delilah, a genetic amalgamation of Demona and Elisa).