Question: What's your opinion on the relationship between Nergal and Ereshkigal?
I think it's tumultuous and sexy. I mean, as sexy as you can get when you're surrounded by dead people all the time.
The myth of Ereshkigal and Nergal's meeting and marriage (which you can read one translated version of here, if you're interested!) is a journey through powerplays and struggles between different rulers, factions and gender politics, all of which gives the two gods at its center a complex and interesting relationship. Quickly redacted, it goes about as follows:
Anu, king of the gods, decides to throw a lavish feast. He sends a messenger to Ereshkigal, sole ruler of the underworld, and expresses his regrets that he would like to invite her, but she can't leave the underworld. Ereshkigal is understanding about this (possibly because of earlier myths that suggest she went to the underworld willingly to keep order there) and decides to send her representative Namtar to the feast in her place, where Anu has promised to pay him all due respect as her proxy.
Namtar goes to the feast, but although all the other gods bow before him and treat him with the respect they would show to Ereshkigal, Nergal refuses, ignoring both the courtesy due a representative of royalty and the frantic attempts of his uncle Enki to signal him to get down on his knees already. Namtar, offended, goes back to the underworld, where he presumably informs Ereshkigal of the situation. Nergal, being hot-tempered and boisterous, claims he'll just march on down there and tell her what's what, which does not sit well with the other gods who are already pretty worried about the prospect of a pissed-off queen of the underworld.
To calm him down and appease Ereshkigal at the same time, Enki convinces Nergal to first build a lavish, richly-appointed throne to take her as a gift when he goes into the underworld. He then carefully instructs him not to eat, drink, bathe or rest while in the underworld lest he not be able to leave it, and especially not to have sex with Ereshkigal. Nergal takes the throne to the underworld and signs in at the gate, but when Namtar sees who's come to visit, he's furious at Nergal's audacity and complains to Ereshkigal, repeating how he was insulted at the feast and implying that if Nergal's offering them offense, all of the other Anunna must be mocking them, too. Ereshkigal is too politically savvy a lady to agree with him that they should blame the entire pantheon for Nergal's misbehavior, so she calms him down and has him send Nergal in.
Nergal is appropriately polite to Ereshkigal and presents her with the throne, and then carefully observes Enki's instructions by refusing to accept any of the food, gifts or help that her servants bring him. When he sees Ereshkigal bathing nude, he even manages to say no to his lust, but when he happens to catch her without her clothes on a second time, he can no longer resist the hotness and they have sex for six straight days. On the seventh day, Nergal wakes up and realizes he's in danger of never leaving the underworld; he asks Ereshkigal to let him go home and promises to come back, but she's furious at his attempts to leave her and not fooled by his lies about returning, and he has to flee, tricking her guards into believing that she said he could leave.
Ereshkigal is devastated by his defection, and Namtar is so distressed by her weeping that he volunteers to go up to the overworld and arrest Nergal to bring him back (and let's be honest, he hates Nergal so this is probably sweet revenge for him, too). She agrees, and, in full infuriated death goddess style also sends a message up to the other gods that Nergal has knocked her up, and if he doesn't get back down here and marry her she's going to open the gates of Irkallu and let the dead swarm the earth and devour the living. Panic ensues, and the gods give Namtar carte blanche to find Nergal and get him back down to the underworld posthaste.
Nergal escapes detection for a while, hiding in various other gods' houss, but eventually Namtar finds him and soundly rebukes him for his behavior. He demands that he return to the underworld with him, and when Nergal tries to refuse he implies that he's too much of a pansy-ass coward to brave the underworld again and face Ereshkigal's wrath. Nergal immediately gets pissed off at the idea that everyone might think he's afraid, and charges back down into the underworld, plowing through its gatekeepers and guards and barging directly into Ereshkigal's throne room. There he drags her off the throne and they have sex on the floor for another six days, and Anu, breathing a sigh of relief at the averted disaster, declares them married and that Nergal will forever remain in Irkallu with his new wife.
Obviously, there's a lot going on here. Ereshkigal is one of the most powerful figures among the Anunna; she's the sole queen of the underworld and worthy of respect from all the other gods, and when she makes threats, everyone immediately goes to Defcon One. Nergal is also an important figure, the princely son of Enlil, and as a result his behavior reflects on the whole pantheon, making the story a direct one of the problems that occur when the overworld gods don't give the underworld its proper dues. There are also strong elements of power struggle between male and female here, with Ereshkigal wielding the power of political clout, royal decree and female sexuality, while Nergal's powers lie in guile and physical violence. Finally, the subtext is all about a political power shift: at the beginning of this story, Ereshkigal's queen of the underworld and the rest of the gods are frankly afraid of upsetting her, while at the end they've managed to not only appease her but also get one of their own number into joint power with her, making it less likely that they'll ever have to deal with this kind of threat of the underworld attacking them again.
Religiously speaking, this myth is relatively "late" or at least "middle" for Mesopotamian mythology; Nergal wasn't overly important in the Sumerian religion and didn't become a major force until he was elevated by the Akkadians, which is why the oldest root myths about the Mesopotamian underworld always refer to Ereshkigal as its only authority and power. Once Nergal had become popular and important enough for the Akkadians to want him included in the affairs of the universe, it's likely that the myth of his marriage to Ereshkigal was invented to legitimize him as an underworld god of equal importance, much the way ancient cults of Poseidon probably decided he was married to Amphitrite as the representative of the sea to legitimize his control over it. The continuum of Mesopotamian mythology also becomes more male-centric over time, so while Ereshkigal has uncontested power in the Sumerian and early Akkadian periods, later mythology began to feel a need to add a man down there, and Nergal, already associated with death, was the obvious choice. Even so, however, Nergal only becomes Ereshkigal's equal, not really her master; even when he comes roaring back into the underworld, breaking her plates and terrorizing her doorman, he just ends up having a bunch of sex and then never leaving her again. Some scholars have sometimes theorized that he fully dominates or even rapes her, based on the image of him grabbing her by the hair to pull her off her throne, but considering that she has lost none of her power and authority in the time he was hiding in the overworld and the other gods were running around panicking, it's more likely that it's just an extension of the wild sexytimes that are about to occur.
So Ereshkigal's and Nergal's relationship is a lot of things: political marriage alliance, competitive royal posturing, sociological evolution and explosively sexual passion. I actually can't think of another divine couple in a similar situation; there are very few gods who bridge the gap from overworld to underworld, hook up romantically and then make that situation work without one or both of them freaking out and blowing things up/causing a massive meltdown/leaving forever. They're equals in power, both feared and respected by all the other gods, and if their myths are any indication, they turn one anothers' cranks like nobody's business. Despite the dysfunctional start, they may be one of the most solid and passionate marriages among any of the pantheons. How weird is it that ancient Mesopotamia actually has one of the highest rates of monogamous love-matches among its gods?
Not that the two of them get along all the time, I'm sure. Nergal has a quick temper and loves to make messes, and Ereshkigal's entire being is focused around preventing any messes from occuring on her turf (not to mention that she has a temper of her own - she and Ishtar are sisters, after all), so I'm sure there are the occasional epic screaming matches and flinging of cosmic powers between them when they disagree on how something should be done in the underworld or one of them sasses the other in front of company. But all signs point to the idea that they also totally rock one anothers' worlds, and you can bet that the makeup sex will be completely out of control.