Wolf Brothers

Wolf Brothers
Battle Cry	Unknown
Founding	Second Founding
Successors of	Space Wolves
Chapter Master	Beor Arjac Grimmaesson
Primarch	Leman Russ
Homeworld	Kaeriol
Strength	Disbanded / Lost
Specialty	Unknown
Colours	Unknown

The Wolf Brothers are were the only OFFICIAL successor Chapter the Space Wolves, made during the Second Founding. Leman Russ had such high hopes about the chapter that he even decided to give them half of everything the original Legion had just to make sure they would be well-off. Russ was hoping that this would be the beginning of a force called "The Sons of Russ" that would eventually form a circle around the Eye of Terror and protect the Imperium, which was later accomplished by the Astartes Praeses.

Well, thing is, the gene-seed couldn't work. The Canis Helix proved to be too unstable (devolving all the initiates into Wulfen DIGGANOBZ), and this, among other matters that were perhaps the machinations of Russ' cyclopean rival or his patron god, would eventually spell the end of the Wolf Brothers and the "Sons of Russ" plan. However, any survivors, if they could even be called that, would sometimes be found. In fact, Magnus actually used the failed chapter as a lesson in utter dickery against the Wolves.

Is this for the better? Depends. How sick would you be if you had a bunch more chapters doing that damn "WOLF WOLF WOLF" meme than just one? On the other hand: if the Inquisition had to deal with a whole PACK of Space Wolves chapters working together like the Dark Angels? Ohh boy, that be interesting to watch. Although, the Space Wolves are exempt from the Legion break-up thanks to the failure of the Wolf Brothers and other such issues. So, it's entirely possible that they do have numerous Chapters that draw from Fenris like the Legion did and simply "forgot" to tell the High Lords.

Note that this issue does not plague the larger Space Wolves chapter, despite Leman Russ having disappeared into the Eye of Terror long ago, implying that access to him or lack thereof has no meaningful interaction with the likelihood of the Canis Helix having an adverse reaction. As the Wolf Brothers used their own homeworld of Kaeriol to recruit, the implication is that Fenrisian natives are some form of abhuman, uniquely resistant to the Canis Helix. Of course, as the Wulfen proved when they returned, while the mutation does effect their psyche, it does not stop them from contributing in battle, so if not for the Imperium's intense hatred of mutants, there would likely have been twice or thrice as many Astartes Praeses chapters guarding the Eye of Terror. This would have prevented so much crap for the Imperium in the future. Welp. They do not go RAAAAAAAAAAAAAARGHHHHHHH!!!!!!!!!!!!!! for some reason.

The abhuman thing is now in question as well, as when Grandpappy Smurf returned and dished out his Primaris Marines, many of them were Terran born or tithes from other areas. That included Space Wolves marines. To make matters even more confusing, the Wolfspear were made without issues, and while there are no Primaris Wulfen yet, it's said that it still affects the Primaris enough that they need to be careful or they'll succumb to bloodlust. The Wolf Brothers just got it really bad. Or drinking Wolf Milk as a baby screwed with Leman's gene-seed thanks to the Canis Helix in it. Primaris Marines come from purest gene-seed prior to the Primarchs being spread. Possibly gene-seed created by the Emperor directly from the Primarch project rather than drawn from the Primarchs' bodies. That said, the original Marines of the Legion and during the Great Crusade were drawn from Terra, as with all Legiones Astartes. So, it is most likely the Canis Helix became part of Leman Russ thanks to his wolven rescue as a baby and it is actually the Fenrisians who have the Canis Helix, not his original gene-seed.