tartysuz

I'm 99.99% sure that my theory that the "mother" is Tiamat is correct. I gravitated to Tiamat in the first place because she was associated with chaos and said to have birthed all the creatures (for SPN purposes: all the monsters) in the ancient Babylonian conception of pre-history.

The appearance of dragons in last night's episodes pretty much seals it. Here's a description of Tiamat's appearance from Wikipedia:

Though Tiamat is often described by modern authors as a sea serpent or dragon, no ancient texts exist in which there is a clear association with those kinds of creatures, and the identification is debated. The Enûma Elish specifically states that Tiamat did give birth to dragons and serpents, but they are included among a larger and more general list of monsters including scorpion men and merpeople, none of which imply that any of the children resemble the mother or are even limited to aquatic creatures.

Applying the above to the SPN universe:

Tiamat may have birthed all the monsters, but she does not necessarily look like the monsters.
Tiamat gave birth to dragons and is otherwise closely associated with dragons -- in fact, Tiamat is a dragon goddess character in D & D. Tiamat is also used in World of Warcraft, which was specifically referenced in the episode.
So far there haven't been explicit connections between this mother figure in SPN and water -- but then again, the show has had a lone siren driving around the Midwest. I'm willing to bet the writers put this detail in the ignore basket. They did hint broadly at this when Bobby said Sam should look to less literal manifestations of the legend that dragon lairs are caves.

If my theory bears out, then the Winchesters would have gone from battling an Abrahamic plot against them and the world as signified by fathers, to a chaotic, pagan plot as signified by mothers.

Hopefully, Samuel succeeds in resurrecting Mary so she can go mama-a-mama against Tiamat!