Please be forewarned, in the interest of calling a spade a shovel, that the following post is mostly pure fanwank. I am going to present a theory and support for that theory that is not only non cannon, but due to the vagaries of certain copyright laws (ironically acting against Games Workshop in this case), it intrinsically cannot be cannon. Regardless, I believe the wonderful aptitude and undeniably beautiful synchronicity of the theory lends it a degree of "Truth" worthy of consideration. But then, I would say that...
Skaven society is an absolute monotheistic theocracy; all Skaven worship The Great Horned Rat. Even Clan Pestilens, who are great friends with Nurgle, carry out their diseased machinations in the name of their Verminous God. The lore of the Skaven was established in the Spring 1986 issue of The Citadel Journal, and though embellished upon to some degree, has remained largely constant ever since, even as the Warhammer world itself was only just starting to be defined, and would remain in a state of flux at least until the early 90s.
"The Horned Rat is feared and worshipped as the patron deity of the Skaven. This mighty Chaos god gnaws at the fabric of the multiverse, instigating the forces of decay."
So The Horned Rat is a Chaos god, a "mighty" one at that, who appears to represent the forces of "decay" or "entropy." But later texts would never mention him in reference to the other four main deities of Chaos. The Horned Rat is not detailed in either of The Realms of Chaos volumes that largely provided the definitive overview of Warhammer's finalized mythology.
As previously noted, The Realms of Chaos were largely the revision that solidified and codified the Warhammer mythos for subsequent editions. That The Horned Rat would then continue to be noted as a Chaos God past that point almost seems bizarre, like a holdover from a prior reality. This renegade Chaos god seems to belong more to a forgotten world of Fimir and Zoats than what Warhammer became. Yet in the 4th edition armybook, The Horned Rat's presence and import is not only reaffirmed, but strengthened by the appearance of his very own Daemonic servitors in the form of The Vermin Lords.
And so for many years and editions the mystery remained, with GW remaining non-committal and oblique. In the Liber Chaotica, there's a suggestion The Horned Rat may simply by a verminous resident of Nurgle's garden, but this raises more questions than it answers.
Then came The End Times. And Age of Sigmar. AoS has its own fluff, and has dealt with The Horned Rat in its own way...
In trying to discover the origin and identity of The Horned Rat, we are looking for a fifth great Chaos God. A renegade among the Chaos gods. One who embodies attributes that define The Skaven, like ruin and destruction, treachery and betrayal.
And what we find is...
MALAL
"One way to look at is that Khorne is
WW2 Wehrmacht, Malal is WW2 SS."
- Tony Ackland
The Spring 86 issue of Citadel Journal saw not only the`second Kaleb Daark comic, but additionally published rules for fielding him in games of Warhammer, and advertised a Citadel miniature set.
Malal, on the other hand, was an intriguing concept, and I'm obviously not alone in thinking so, as he immediately began to be incorporated into the burgeoning Warhammer mythos. From what I can make out, he was originally intended to share a place in the pantheon with Khorne, Nurgle and the others, a suspicion confirmed by the place I first encountered him, the first edition of WFRP:
MALALADY
Malal was originally intended to be a part of the Realms of Chaos pantheon, and artist Tony Ackland did a number of concept sketches delineating Malal's pantheon of Daemons.
"They were concept illustrations of lesser daemons that were not used. I think that the insectoid ones were for Malal. I think it was that one was the riding beastie, and the other one a kind of war dog. I don't think that Malal himself was particularly insectoid though. This was probably me just trying to give vent to my inner entomologist when I started designing the daemons."
-Tony Ackland
The final official published appearance of Malal (with one notable exception in Hogshead's continued WFRP line) worth mentioning was in the 1986 short story collection Ignorant Armies, within the story entitled "The Laughter of Dark Gods", by William King. Interestingly, the story features the death of an unnamed albino champion of Malal, whose warband wandered the Chaos Wastes.
THE CASE FOR
- Congruence - Both Malal and The Skaven and The Horned Rat are introduced into the Warhammer world at roughly the same time.
- A renegade Chaos God - Malal is a "Mighty Chaos God" just like the Horned Rat, but has turned against the other Gods and stands outside of the main group of Khorne, Nurgle, Slaanesh and Tzeentch. He is known as "The Outcast God", "The Lost God" and "The Renegade God." Likewise, The Horned Rat has no defined connection to the Chaos Pantheon, is "lost" from the primary mythos.
- Corresponding Attributes - Malal is the incarnation of the concept of Destruction, including self-destruction, just as the Skaven embody destruction and ruin, up to and including being a bigger danger to themselves than others. "Everything they touch is destroyed. Be if from plagues, their 'science' or their backstabbing nature." (5) Malal also represents betrayal, and one of the primary characteristics of Skaven is there penchant for treachery and betrayal. "The nature of Malal's powers is parasitic" (1), while the Skaven are vermin, parasites of human society, and The Horned Rat " gnaws at the fabric of the multiverse."
- Visual Similarities - The images of Malal and his Greater Daemons, and that of The Horned Rat and his Vermin Lords are strikingly similar:
- I'm not the first to make this connection - in researching this article, I came across a forum discussion on this very topic from 2009. (5)
THE CASE AGAINST
1. Their Numbers are Different - All Chaos Gods are associated with a number, Malal's is listed as "11," while The Horned Rat is associated with the number "13."
Practical Rebuttal - While the Skaven hold the number 13 as important, this doesn't necessarily mean it's The Horned Rat's number in the same way as the numbers assigned to the other Chaos Gods. Vermin Lords have no powers or benefits associated with 13 in the same way as other Daemons commonly have effects tied to the number of their Chaos diety.
Fluffy Explanation - Malal's number was eleven, but when he was cast out by the Other Chaos Gods, he took the number 13.
and
2. Kaleb Daark fought with the Skaven - rather than being aligned, Malal's champion, in one of his few documented exploits, battled against the Skaven.
Practical Rebuttal - like its uncommon for creatures of Chaos to fight each other. And Skaven's propensity for in-fighting is generally cited as the major reason they've not swarmed up en masse and taken over The Old World. Not to mention that self-destruction is one of Malal's things. Additionally, the proposition that The Horned Rat is Malal does not by necessity include any awareness of this by The Skaven.
Fluffy Explanation - Malal assumed the identity of The Horned Rat to hide from the other Chaos gods intent on hunting him down. To aid himself in this, and throw the other Chaos gods off his track, he sowed discord between the "loud and proud" champions of Malal and the Skaven followers under his guise as Rat-God.
CONCLUSION
POSTSCRIPT:
MALAL'S LEGACY
1 - Orlygg Jafnakol. "The Malignancy of Malal: Solving the mystery of the 'fifth chaos god'." January 19, 2013.
http://realmofchaos80s.blogspot.ca/2013/01/the-malignancy-of-malal-solving-mystery.html
--"The Malignancy of Malal: Malal's Daemonic Pantheon Restored?" January 21, 2014.
http://realmofchaos80s.blogspot.ca/2014/01/the-malignancy-of-malal-malals-daemonic.html
2 - Bellarius. "Why Are Warhammer Fans Obsessed With Malal?" December 24, 2015.
http://thegoodthebadtheinsulting.blogspot.ca/2015/12/why-are-warhammer-fans-obsessed-with.html
3 - Various Contributors. "Warhammer 40000 Wiki: Sons of Malice."
http://warhammer40k.wikia.com/wiki/Sons_of_Malice
4 - Larry Vela. "The Gods GW Hopes You Forget." September 22, 2016.
http://www.belloflostsouls.net/2016/09/the-gods-gw-hopes-you-forget.html
5 - Various Contributors. "The True Name of The Horned Rat." November 22, 2009.
http://www.warseer.com/forums/showthread.php?231945-The-true-name-of-the-Horned-Rat-(-)