A Transient Divinity
The Leveller, as Forrest once suggested, is neither good nor evil, merely one more force at work in the Mythworld with its own agenda. In this case that agenda is population control. We know that the Trow were rather fond of genocide, back in the day. Some force, possibly Wyrd, kept throwing a new sentient race into the mix roughly every millenium and the Trow would always enslave it, hunt it to extinction, or both. For a very long time they must have been the undisputed dominant race of the Mythworld. This ended when they were sickened by what they had done to the Cailleach and the Oghres, which we are told happened right around the Axe Age.
Humanity, at this time--and presumably all the humanoid races as well, from ghols to dwarves to Skrael--were just finishing up with their respective evolutions into sentient life. These "Young Races" would normally, in the grand scheme of things, be KIKd into oblivion but for whatever reason the Trow had given up that role and so they survived--which is why the Mythworld has so much biodiversity, at least in the sentience department. Which causes a problem in its own right: the Young Races are pretty much universally belligerent, given to fighting between and amongst themselves, and the result is one very bloodsoaked planet.
Enter the Leveller. I don't claim to know where this thing came from, where it is now, what it looks like in its true form but based solely on its apparent effect on the Mythworld my theory is that it serves as a check against any of the Young Races becoming predominant or dangerously over-populated. According to this scheme the Leveller would be a kind of maintainer, stepping in while Wyrd is away to keep the Mythworld from boiling over. Neither good nor evil, nor orderly or chaotic, the Leveller operates in such a way to preserve the status quo. It does so by inspiring indiscriminate and worldwide butchery.
Now, the general consensus among Mythworld scholars is that the Leveller is a bad thing. In an earlier post I suggested that this is due to the pragmatism of the scholars. With their own mortality in mind, they will tend to think that anything which kills people is evil. From the Leveller's omniscient perspective it feels itself to be doing good, important work, helping the Mythworlders to keep control over themselves and their (otherwise) unchecked growth. Whether or not anyone agrees with the Leveller is immaterial; as a divinity it feels that it knows best.
The Leveller can only, apparently, act by influencing the minds of the truly powerful Mythworlders--those who come closest to its level of omniscience (close being a relative term, here). Anyone who reaches a certain level of power will automatically come under the Leveller's scrutiny; those who become predominant among the young races (so far only humans, since they seem to breed the fastest and have the most access to magical "technologies", but I don't see any reason why there couldn't be a ghol Leveller) will be chosen to be avatars of the god-thing itself.
The obvious argument against this is that the truly powerful ought to be able to protect themselves against this possession. It is my belief that power, in the Mythworld, always comes with a price. It tends to unhinge even the sharpest mind; at the very least, it requires that one take on certain vulnerabilities--for instance, a truly powerful sorceror will have a true name that must be protected, while a truly powerful warrior will wear a suit of magic armor that protects him utterly except in one vital area, or will be under some kind of protective spell that means he can only be killed by his own sword, etc. Sometimes the vulnerability is even closer to home--the Watcher could only be killed by arrows tipped with fragments of his own bones, suggesting that the truly, remarkably powerful people can only be hurt by something equally powerful--namely, parts of themselves. Balor, our premiere Leveller Avatar example, suffered a similar vulnerability: Alric was forced to become his "equal" in order to defeat him.
The Leveller seems especially fond of political leaders, which doesn't seem that strange--these men and women are the ones who are most likely to lead their given peoples into genocidal wars and also, regardless of their personal talents, they are the most likely to be in possession of the strongest artifacts.
One aside here: these powerful people are often aware of their own weaknesses. I would argue that Connacht sought to destroy every artifact he could find because he did not want any of them tainting him and bringing him to the Leveller's attention. We know that the Heron Guards are the best-informed scholars on the Cycle, the Leveller, etc.; I would guess that one of them, operating as adviser to the Wolf, suggested to Connacht that the Tain, Balmung, etc. could corrupt him and because he was a smart fellow he got rid of them. To no avail, of course--perhaps he kept his magic armor, thinking it was too valuable to give up, or perhaps the Leveller found a better crack in his defenses.
The Leveller corrupts these people of power by exploiting their weaknesses. Its powers are all suggestive. I would even go so far as to argue that it has no direct power whatsoever, and is merely an influence: it communicates not in words but in visions, and inspires its Avatars by giving them a small portion of its own perception. These avatars are ambitious people to begin with. When they are allowed to see the world from a godlike perspective, if even only for a few scattered moments, they begin to think of themselves as demigods and they act accordingly.
I do not think that the Leveller's avatars think of themselves as evil or in any way required to destroy. I think they continue onward with their original agendas, fulfilling their own dreams. The only difference is that having seen through the eyes of a God they can no longer function as well-adjusted human beings--they lose the virtues of compassion and sympathy and see death as a necessary thing which is not to be feared or avoided, but embraced.
One more aside: the reason why it is always the great Hero who becomes the Leveller Avatar is simple enough. To defeat a Leveller Avatar, one must get one's hands on all the power available. Alric was forced to seek out artifacts and learn new spells to defeat Balor. In the process, he increased his own personal power severalfold and became the world's greatest mage. Also during this time he made himself the undisputed ruler of the entire free Mythworld. These things were necessary, as far as he could tell, because he had a job to do: to defeat Balor. They will, however, bring him to the Leveller Divinity's attention and as a result will lead to his eventual corruption.
So the Leveller avatar goes about his business, but with a new perspective. The result is horror and war but as far as the avatar is concerned, this is acceptable. The other denizens of the Mythworld, without the benefit of this long view, see the Leveller as Ultimate Evil, and react accordingly. The result is to thin the populations of all the Young Races, kill off a few more of the remaining Trow, and generally keep balance across the board. The survivors rebuild and go on with their lives until the next cycle. The Leveller is satisified--it doesn't want extinction, merely balance, and so its work is done. If it truly wanted to annihilate the entire Mythworld this would be well within its power; barring some kind of bizarre connection to the comet, it could raise avatars every year if it wanted to. Once in a millenium is all it takes, and hence the cycle (Perhaps the Leveller's idea of time is so stretched out that a millenium is, to it, a single moment). Losing an avatar means nothing to it. Balor's premature death still had the desired effect and the aftershocks of that particular avatar--namely Soulblighter--are enough to keep the balance. Therefore, the cycle is not broken. The quality of life under the current "dark age" is different this time but the Leveller is thinking in terms of eternity, not whether a given bunch of Mythworlders are happier than they were two thousand years ago. It IS a dark age for some of the Young Races, specifically the Ghols and the Myrmidons, who really got the short end of the stick this time around.
The most interesting part of this theory for me is the suggestion that the avatars are not driven to destruction by the Leveller, but only to a change in the way they do what they had in mind anyway. We know very little of previous avatars, other than most of them were interested in conquest. Well, they were presumably political leaders before they were corrupted, and conquest is just politics when the gloves come off. The real evidence I wish to present here is the case study of Connacht/Balor, whose history provides a perfect example of what I'm talking about.
Connacht was the greatest hero the mythworld ever knew. Politically he was master of most of the continent; in terms of military prowess he was unequalled; he possessed numerous artifacts so powerful that they remain mysteries to the current era (the Tain, in particular). He is the most obvious candidate for Leveller Avatar status in recorded Myth history. He was also the biggest threat, as far as the Leveller Divinity was concerned: he did manage to get rid of an entire young race (the Myrkridia) and imprison the Trow, which could have thrown the balance of power in the Mythworld completely off kilter. By forging deep alliances with other young races (the dwarves, the berserks, and so on) he threatened to create an unstoppable power bloc.
His main motivation seems to have been to consolidate power by diplomacy or trickery. It was crucially important to him that he become emperor of the Cath Bruig not out of love for his people but because this would let him control the middle of the playing board, so to speak. He seems to have wanted, as SiliconDream has suggested, to restore order to the world and free it from its bloody history, to contain his enemies and allow his friends to prosper. In this he was remarkably successful. The Leveller Divinity could not allow this to continue.
We don't know what happened to Connacht after he ushered in the Wolf Age. There are suggestions he went into self-imposed exile, and that his Lieutenants did the same. I think he was trying to "break the cycle" by refusing to allow himself to be touched by the Leveller. So he went into lands which he believed to be outside of the Leveller's jurisdiction--either he sought out Faraway, which is described as a place where there are only light ages, and therefore no Levellers, or he went into the untamed lands where his power was meaningless and therefore he wouldn't be such an easy target. It's even possible that he changed his name to Balor intending to confuse the Divinity.
The Leveller Divinity, of course, could have chosen another avatar, and may even have inspired Damas to become Soulblighter or the Watcher to become such a threat but in the end, Connacht remained just too tempting a target and it was he who was corrupted. There was no escape, no matter how hard Connacht tried.
So he returned to the known Mythworld, gathering his armies slowly, now unable to remember why he had been so nice to people when they were little more than insects. He tricked the Myrmidons, helped the Ghols overrun the Dwarves, and finally he returned to Muirthemne.
As far as Balor was concerned he was still Emperor of the Cath Bruig. The Ibis Crown was his by right, as well as the remarkable power base that Muirthemne represented. Realizing that the Heron Guard was against him now (though he couldn't know why, and probably didn't care) he sent Soulblighter (his oldest and dearest friend--what did it matter if Damas had cut off his own face? To a God that was nothing so extreme) to distract them at Bagrada. He then demanded the crown from the Emperor, who he would have seen as an unlawful usurper. When Ceiscoran (or whoever it was) refused to hand it over, Balor destroyed the entire Empire because he knew he needed that crown to consolidate his power. The deaths of all of his former subjects meant nothing--human lives are meaningless in the face of eternity, which is what Balor was looking at all the time now.
He couldn't find the crown, which must have peeved him immensely--it was his by right!--and now he discovered that he had just wiped out all the people he had expected to lead. No matter, though, he could still lead them even if they were dead--he merely had to animate their corpses.
He then made camp--and regrouped. He drew the Fallen Lords to his service one by one, because he wished to accrete power. He brought back the Trow because he thought they might be useful. The Myrkridia he did not want--he was still Connacht in his heart, and Connacht would never ally himself with those monsters, no matter how useful they might be. He had a fortress built at Rhi'anon because it was the most easily defensible place he knew of.
Then something went wrong. Humanity en masse didn't support him. He couldn't really understand why--wasn't he their greatest hero? By this point he was incapable of understanding normal human motives or prejudices. When the Nine formed to oppose him, he decided that THEY must be the bad guys, since they stood against his effort to bring order and law to the entire Mythworld. So he did what Connacht had done to the Trow--he went after their cities and started plowing them under. They were a threat to his agenda of order, so they had to be eliminated. He did not destroy them as utterly as he had destroyed Muirthemne, but only because he didn't think of Madrigal and the Free Cities as his by right. This must have been the same logic that lead Connacht to imprison rather than slaughter the Trow.
When Alric was captured and brought before him, Balor was confused. Here was an Avatara claiming to support the cause of the Light, someone who pleaded that Balor's depredations were in some way wrong, when Balor was absolutely convinced that he was still acting with humanity's best interests in his heart. He did not have Alric killed, either because he was smart enough to realize that the Avatara had a point (power recognizes power, even at the demigod level) or because he truly thought he could win Alric over, just as he had done with the Fallen Lords.
Alric returned to Madrigal, having escaped because Balor was unfamiliar with the new technology of balloons (he couldn't prepare for the Five Champions because he couldn't imagine any way for them to cross the Cloudspine during winter). Balor did his best to get Alric back, finally attacking and sacking Madrigal, but to no avail. Meanwhile, Alric, having gotten some inkling of what was going on, consulted with the Head and with his Journeymen and learned just who and what Balor was. Realizing that Balor was all but unstoppable (Connacht, after all, had defeated Moagim Reborn rather handily, and Alric knew he was not yet the equal of that Leveller Avatar), Alric decided to do the unthinkable--to make himself the equal of the greatest Hero the world had ever known. The rest of Myth TFL is the story of Alric's terrible bargains.
In the end, Balor was defeated by his own weaknesses--the same weaknesses which had allows the Leveller Divinity to invade Connacht's consciousness. Connacht had trusted his lieutenants implicitly. Balor did the same and paid for it dearly--by trusting that the Deceiver and the Watcher knew what they were doing, he allowed them to fight amongst themselves and blunt a good portion of his armies in the process. Connacht had grown up in a world where the biggest threats were animals like the Myrkridia and giants like the Trow. He was used to fighting pitched battles where strategy was all on his side. When Alric attacked Balor with his entire force merely as a diversion, Balor couldn't see through it; his enemies had always been straightforward. Finally, Connacht had possessed no equals and had always gone into battle knowing that he was personally more than a match for any one given enemy. When Alric seemed to have thrown in his lot with the hated Myrkridia, Balor attacked him personally, not realizing that with the Eblis stone Alric had become his equal.
When Connacht defeated Moagim Reborn it must have been on a very different playing field and both of them must have been far less desperate. Alric won against Balor not because the cycle was broken but because Alric was willing to take steps that no Great Hero before him had ever considered necessary.
This, then, is my theory. The Leveller is not evil, but instead a force for population control. It does not inspire its avatars toward conquest or destruction but merely gives them an altered perception of their own goals and allows them to act in ways they had previously considered unacceptable. The cycle is not broken at all, it has merely turned out differently this time than it has in the past.
The main arguments against this, of course, come from GURPS and the epilogue to Myth 2. As to the latter, it is the opinion of an obviously prejudiced Heron Guard. The Guard, since they live so much longer than normal human beings, are the ones most likely to have some knowledge of what's going on but because they do not seek power for themselves and because they possess a rather naive view of good and evil (necessary because their politics are so dramatically polarized) they don't understand its more cosmological applications.
As to GURPS, well, I've never been a fan, but I think in this instance it can be discounted as well without being actually dismissed. For one thing, it fails to say whether the cycle is broken or not. For another the information it gives on past Leveller avatars and past heroes is sketchy enough that it does not actually disprove my theory (though if someone finds evidence to the contrary, I'm more than willing to listen).
I've thought this through quite a bit and I really think I'm on to something here. I am not so naive, however, as to think that everyone is just going to accept my theory on the spot--nor to think that I've come up with the definitive answer to the most intriguing question Myth raises. So let the responses begin!