Fenrir's Chosen was a neo-Nazi group formed by some of the members of Empire Eighty-Eight after the death of Kaiser. Their gang symbol was a wolf's head, which they would wear as face-paint.
Creating a group of warriors that followed Hookwolf's philosophy and code - creating "Aryan" warriors who were intended to surpass ordinary mercenaries and police. They were known for being incredibly unsubtle and, of course, racist.
Recruits to the Chosen trained with melee weapons as well as guns and unarmed combat, leaving them physically exhausted. The parahuman leaders would single out individuals who had a killer instinct, who would then be challenged to fight them in single combat as an induction into their elite. 
They would steal supplies sent in as part of the post-Leviathan relief effort. They were known as an unusually aggressive, violent group who thrived in the chaos that followed the attack. They were known to participate in the slave trade, kidnapping people from their homes and farming them out for slave labor.
When Shatterbird recruited Hookwolf, she blackmailed him by leaving notes telling the Slaughterhouse Nine to destroy them as part of his "tests", promising to leave them alone only if he willingly joined.
↑ 2.02.12.2Fenrir’s Chosen Founded by Hookwolf after Kaiser’s passing, Fenrir’s Chosen (The Chosen for short) are comprised of the more violent, hostile and aggressive wing of the old Empire Eighty-Eight. Their squads are seizing supplies that the local authorities are attempting to distribute to those who have remained in Brockton Bay following the Endbringer event. - Cast (in depth)
↑Coil had provided the map, and Tattletale had provided the details. Various symbols and gang symbols marked out spots where enemies were lurking. Stars for the nobodies, the M with the two ‘dollar sign’ vertical lines struck through it for the stragglers from the defeated Merchants, and a wolf’s head for Fenrir’s Chosen. - Excerpt from Interlude 15.y
↑‘Fenrir’s Chosen’. Each of the thugs had white face-paint extending from forehead to cheekbone to chin, in a crude approximation of a wolf’s face. - Excerpt from Sentinel 9.6
↑His own were marked out in clear, blocky letters, noting priority, naming locations for what they were and briefly covering the nature of the operations these crooks and gangs were conducting in his territory. Low level drug dealers and looters here, some Chosen dragging families from their home and selling them off as slave labor over there. - Excerpt from Interlude 15.y
↑“The individuals in question are Menja, Stormtiger, Cricket, Rune, Othala, Niflheim and Muspelheim. I’ll see you have all available records. Best to enter any confrontation with your eyes wide open.” - Excerpt from Interlude 19.x