After studying myths and religion for so long I am seeing links to different ideas and gods. I seem to see links that other are missing, which surprises me. The link I see now is with an interesting character of Greek myths known as Echidna.
Echidna, the mother of monsters and wife of Typhon, the terrible giant whom fought the gods. There are diverse ideas of her parentage, but the parents that seem most plausible are Gaea(the Earth) and Tartarus(the pit, basically Hell.) She has connections with the earth element, living in a cave, so her other possible parents, Ceto and Phorcys, 2 sea deities, are unlikely.
She appears as a beatiful woman above the waist, but as a serpent below. This makes her a Dracaina, a dragon-woman. Dragon women almost always have comely human features and can be quite enticing to human men. She married Typhon though, her brother. With him she bore many monstrous children. The sphinx, Cerberus, Orthus, the Hydra, the Chimeara, etc... Typhon was urged by his mother, Gaea, to make war with the gods after they imprisoned her children, the Titans. They lost this war, leading to Typhons being imprisoned under Mount Etna and Echidna living in the cave Arima. Zeus allowed her and her children to live so that heroes had challenges. Later Herakles (Roman name was Hercules) met her and after a time, he too fell to her charms and she bore him 3 sons. One of them, Scythes, became a great Scythian king and passed his name onto those Asian peoples.
Later, the hundred eyed giant, Argus, killed her as she slept, on orders of Hera, the queen of the gods (they don't really say why, maybe because she produced children with Herakles.)
She sounds very familiar to another goddess, an ancient goddess from Mesopotamia. Tiamat, the mother of gods and monsters. The great mother goddess, the primoridial sea of chaos. She mated with her other, Apsu, the primordial waters of the the dark abyss under the earth and birthed the gods. The absolute silence they were born into and lived was no longer though and so they consipired to kill their offspring and all their progeny. The god Enki/Ea learned of this and warned the gods. He then poisoned Apsu, killing him. In retaliation Tiamat birthed the dragons, sea serpents, merpeople, scorpion men, the lion-centaurs, and others to form an army. Her son, Kingu, joined her cause and became her new significant other. She bestowed in him the tablets of destiny and he made war against the gods. Marduk, the god of storms, had claimed kingship over the gods and so was to fight against them. He slew Kingu, taking the tablets of destiny for himself and creating mankind from his blood. Then after a lengthy, stormy battle he slew Tiamat, splitting her into two and forming the earth and sky from her body. This shows that she not only had sea and chaos connections, but to the earth as well. She is a primordial goddess and is thought by later peoples to be more dragon-like, though we don't know how the ancient Mesopotamians originially imagined her.
Here we see the connection with Echidna, a dragon woman, mother of monsters, mated to someone who fights against gods and is defeated. Tiamats monstrous children were allowed to live and serve the gods and aide mankind as guardian spirits, similar to Echidnas, though her children hurt mankind, they gave challenges to heroes, which is needed. The 2 are the same. The Greeks took the stories coming in, and added it to their own. This is nothing unusual, as they did it all the time.
The movement of the mesopotamian great mother goddess Tiamat, up to the Greeks as a minor goddess, moved up even further. Another connection I see is that of the Norse Angrboda. She was a giantess and her name means "one who brings grief." She is also called the "witch of the ironwood," the place were giantesses live. She was the mother of the world serpent Jormungandr, Fenrir, the great wolf, and Hel (also called Hela,) the goddess of the underworld and where we get the world Hell from. She bore these children with Loki, the evil trickster of the gods, and the son of a giant himself. Her son Fenrir was raised by Odin, but had to be chained, fated to one day kill his foster-father at the end of time. Her other son, Jormungandr, was tossed into the ocean, where he grew so large he circled the Earth. He will one day fight Thor and be killed by him, but not before delivering a fatal dose of venom to Thor, killing him moments after the battle. Hel was givent he domain of death by Odin. She was born with half her body being pitch black (I have also read that she is half rotten corpse, though this may be from modern writers) and having a gloomy disposition. She rules the underworld and is the judge of the dead. Only those who die as brave warriors go to Valhala, basically Heaven, the rest go to Hel's realm. She is the enemy to all, only in the form of Death, cold and without mercy. She takes from all, equally and is the only of Angrboda's children to be honored and to survive the end of the world, watching over the dead.
Angrboda is also thought to have then mated with her son, Fenrir, to produce a brood of giant wolves, Hati and Skoll, who chase the sun and moon across the sky, and Garm(also Garmr) the guardian of the underworld. Garm is just like Cerberus, who is a son of Echidna. The connection here, to Echidna and Tiamat, is of a supernatural woman mating with a man who wants to destroy the gods to produce monstrous offspring to battle the gods.
Echidna, Tiamat, Angrboda, they are all the same. An ancient image passed down through the generations and cultures. A primordial goddess, mother of monsters. She was said to have been defeated, but she keeps returning to mother more monsters across the world. I am sure she is found in other cultures, but these are the only connections I have found as of now. Honor her, honor the mother of chaos and pray.