Fenris

"There are no wolves on Fenris."

– Popular saying during the Great Crusade

Even the tyranids would need a blanket here.

Fenris is a frozen little hellhole in Warhammer 40,000, most notable for being the home world of the Space Wolves. Named after the ancient Viking wolf monster involved in Ragnarök (because the Space Wolves are also Space Vikings, at least at first glance), Fenris is located in the Segmentum Solar, near the borders with Segmentum Obscurus, Ultima Segmentum and the Eye of Terror. As of 8th edition, it is also slap-bang in the middle of the eye-of-terror-like, galaxy wide rift called the Cicatrix Maledictum. Its population is currently decimated, thanks to a certain cyclops slaughtering everyone who lived there in order to bring Prospero the Planet of the Sorcerers into the material realm (aka *normality*).The Imperium in all politeness, classifies it as a Death World, meaning that everything in the planet's biosphere is lethal and will always try to kill you and most of the times succeed. This makes it the ideal place to recruit for an army of space vikings.

Fenris is composed of a single continent called Asaheim (Literally translating to Home of Gods in old Norse), with hundreds of sinking-and-reforming islands in its vast world sea. Those parts of Fenris which aren't completely frozen over can only sustain human life for no more than a few minutes, and alternate between being frozen and undergoing earthquakes. The Fenrisian wolves are among the most dangerous predators in the galaxy, as they can reach the size of a full-grown horse. The dominant sea life are octopi-like monsters called Kraken, and they have tentacles that can reach miles in length -- some paranoid types have claimed that these may actually be stranded, devolved remnants of a past Tyranid invasion, just as they claim is the case with the notorious Catachan Devils. Presuming the “Kraken’s Egg” in the Fang actually is one of their eggs, then these suspicions are true; Magos Biologis were permitted to examine it in 999.M41 and declared it to be of Tyranid origin. There are also bipedal, anthropomorphic... things ...walking about the snow of Asaheim that the locals refer to as trolls, and a fox like creature that has shifting camouflage and is known as a Doppelgangrel. There are also the Wulfen- abortive Space Wolf neophytes that have devolved into Digganobz Wolverine lookalikes wolf-like monsters. All in all, it's one of the deadliest planets in the galaxy.

And the Space Wolves love every minute of it. They are served by its Planetary Defense Force, Kaerls.

Exactly why a whole planet resembles an exaggerated Viking theme park is unclear. The most we know is that the Emperor alluded to it as “a charming experiment in reconstructed mythologies” from the Dark Age of technology. This would give the impression that someone, somewhere deliberately engineered a frozen hellhole full of monsters and murder just to live out their Viking fantasies. It would also give the impression that people who did engineer Fenris probably got their understanding of Norse Mythology from DnD Monster Manuals and Marvel Comics, or possibly from the Norscans of Warhammer Fantasy fame. The fact the Emperor thinks that it's "charming" should also tell you everything you need to know about the fellow, if you somehow didn't already. (So, it was literally meant to be a theme park, like WestWorld.)

Fenris as a planet is a cold near-iceball kept marginally livable due to extremely violent geologic forces. Its orbit is elliptical and inclined with a short apsidal period, squeezing the planet in all directions like a stress ball and causing its surface gravity to vary from .9 to 1.2 G over the Fenrissian year while causing the relatively shallow encircling ocean to cyclically freeze and melt. Only one landmass on the whole planet exhibits the stability of a continent, and that's the Fang itself. All other islands are very short lived, made of ash permafrost around a volcanic core with lifespans measured in centuries at most as the rapid glaciation cycle of ice, melt, and earthquakes causes them to shatter and collapse. But new volcanic islands are always rising as the sea crust is thin and the mantle is very active. What life persists (human and otherwise) is locked in a continuous cycle of relocation, risking the waters and ice to find newly raised lands to occupy as the old crumble away, whilst sea life must constantly avoid the regions away from the sun. It may be only a close balance of volcanic albedo that keeps Fenris's seas from freezing completely. The furious inner workings of Fenris also power fantastic aurora, just in case this wasn't enough of a Viking paradise to begin with.

It has been invaded four times:

1. First in M33 by the Thousand Sons and Magnus himself, who lured most of the chapter away, brought a million-numbered army of mortal cannon fodder, laid siege on the Fang, successfully broke in, destroyed an experimental Wulfen curse cure, killed a whole bunch of awesome guys including the current Great Wolf and almost including Björn, and then teleported away with his Thousand Sons and their ships, avoiding any major loses (aside from that massive army of mortals, which he left behind as a distraction). Space Wolves somehow decided they won. (Mostly because the Leader of the Wolves REALLY REALLY hurt Magnus. Space wolf style! Basically he beat Magnus down really hardly after falling off the massive mountain that is the Fang, punching him into a wall, ripping off his skin revealing a humanoid cloud of light, making Magnus yell out in pain and almost ripping out Magnus's eye. Magnus recovered in a spectacular way though. That being catching the Wolf Lord's fist then literally annihilating his soul with a flick of his wrist. THOUSAND SONS FOR THE WIN FURRY FUCKS!!!!)
2. Second one was during the Age of Apostasy by the mad cardinal Bucharis, who failed miserably despite having a 10,000 to 1 advantage in manpower. He actually managed to lay siege on the Fang but failed to do anything to it (unsurprisingly, given TS needed custom strike cruiser turned into a giant plasma cannon to break through the fortress's void shields, and even they they didnt manage it for WEEKS), until the companies, who where stationed on their ships when his fleet arrived made a planetfall behind his army and sandwiched it between themselves and the defenders of the Fang, massacring it to a man.
3. Invaded after the First War for Armageddon by a combined force of Ordo Malleus, Grey Knights and a Space Marine chapter during which immense badassery ensued as Logan Grimnar 1) Killed a Grandmaster and some Justicars and 2) Killed the Inquisitor trying to fuck with him. Bjorn the Fell Handed convinced him to negotiate a cease fire because there was more cheese than his space furries could handle. Since then the Inquisition has avoided Fenris.
4. Invaded at the same time as the 13th Black Crusade and Gathering Storm with the Grey Knights and Dark Angels deceived by Tzeentch into invading Fenris on accusations of the Space Wolves committing heresy via sheltering mutants. Magnus and the Thousand Sons then show up to personally screw the entire Fenris System with the loyalists caught up in it. While they were driven back, the worlds of Fenris were highly damaged and Magnus got the last laugh by using the slaughter to summon the Planet of Sorcerers into orbit around Prospero (all while the Eye of Terror expands after Cadia cracked and split the galaxy in half).

In all three of these examples the harsh environment of Fenris scored more kills than the Space Wolves, which is something to say when you are competing with more than a thousand viking superhuman killing machines.

Round 4 aka Yiff in Hell

Recently Fenris has been attacked again by Chaos forces and GW has really made it clear things are going bad for them, with the Dark Angels severely damaging at least one planet in the system, Midgardia.

Then Magnus the Red and the Thousand Sons show up, ready to pick up where they left off last time. Yeah, things are going really well for the Wolves.

Magnus succeeds at killing many Fenrisians in the most disturbing and cruel way, but ultimately gets banished for his trouble (although later events would reveal that even this was just a part of the Daemon Primarch's plan). Then the Inquisition and Grey Knights proceed to wipe the those countless thousands of surviving Fenrisians who had fought against the daemon incursion, because now they're tainted by Chaos, and this time the Wolves aren't complaining about it lest they suffer another attack by their old foes. It also meant having to open their doors to the Inquisition; and now the Ordo Hereticus are frequent visitors, no doubt using the conflict as an excuse to get their foot in the door and keep tabs on the chapter. However, they're still a First Founding chapter, and the impressive sacrifice of two Wolf Lords in the 13th Black Crusade combined with the innate stubborness of the Wolves mean that they're far from the Inquisition's bitch.

In the aftermath though, the Rune Priests proclaim that the spirit of the World Wolf is whole once more, yet new, more terrifying monsters would stalk the wilderness and give the Fenrisians (who already dealt with Krakens and Werewolves) something new to deal with.

The other planetary bodies of the system were also significantly damaged:

Midgardia was infested by a plague designed by Mortarion and was subjected to two exterminatuses (exterminati? exterminata), first by the Dark Angels, then by the Wolves themselves due to the bulk of the planet's life residing underground and out of the way of the first Exterminatus, absolutely obliterating it. Shards of Midgardia continued to fall to other planets for years, infecting anyone nearby with horrible diseases.

Svellgard was once an ocean world, but Midgardia's destruction caused solar flares which boiled away the water, leaving it a glassy, salty desert planet.

Frostheim had its ice melted away by warpfire induced by the Alpha Legion, leaving a thick layer of prehistoric bone that was said to come to life and hunt for the blood of the living under the sign of the new moon.

Fenris' own moon Valdrmani was rendered into a hellish wasteland, but was reconsecrated and rebuilt into an astropathic relay station.

The world had a population of less than 3,400,000 before the war broke out, now undoubtedly reduced following the planetary invasion and subsequent civilian purging by Grey Knights due to their exposure to daemonic forces. Coupled with the revelation that exposure to the Wulfen Curse is contagious, seeming to accelerate it's eruption in other Space Wolves, it may mean the chapter is doomed to either die out, mutate into Wulfen, lose their sanity and go renegade to fight Chaos like the Wolf Brothers before or some combination of the above. If only they had that cure Strawberry destroyed the first time he attacked... At least the space yiffs would get their chance to go down in a blaze of glory, seeing as the 13th Black Crusade starts pretty much immediately after the Fourth battle for Fenris.

However, the creation of the Wolfspear, Primaris reinforcements and along with the fact that GW isn't likely to kill off one of the most popular first founder chapters means that the Space Wolves will still live on. The Primaris Space Wolves seem to be resistant to the Curse of the Wulfen's physical effects, but it still can cause them to go into a bestial rage at times.

Coupled with the restoration of the defenses of Fenris, the Space Wolves, while not at their same strength prior to the Siege of Fenris, will likely not be going anywhere soon.